diff --git a/modules/environment/domain/Invariant.ts b/modules/environment/domain/Invariant.ts
index 13ef7c67..1044c2ed 100644
--- a/modules/environment/domain/Invariant.ts
+++ b/modules/environment/domain/Invariant.ts
@@ -1,6 +1,8 @@
 import Requirement from "~/domain/Requirement";
 
 /**
- * Environment property that must be maintained
+ * Environment property that must be maintained.
+ * It exists as both an assumption and an effect.
+ * (precondition and postcondition)
  */
 export default class Invariant extends Requirement { }
diff --git a/modules/system/application/UseCaseInteractor.ts b/modules/system/application/UseCaseInteractor.ts
new file mode 100644
index 00000000..52c26b59
--- /dev/null
+++ b/modules/system/application/UseCaseInteractor.ts
@@ -0,0 +1,61 @@
+import Interactor from "~/application/Interactor"
+import UseCase from "../domain/UseCase"
+import type { Uuid } from "~/domain/Uuid"
+
+type In = Pick<UseCase, 'id' | 'name' | 'primaryActorId' | 'parentId' | 'extensions' | 'goalInContext' | 'level' | 'mainSuccessScenario' | 'preCondition' | 'scope' | 'stakeHoldersAndInterests' | 'successGuarantee' | 'trigger' | 'solutionId'>
+
+export default class UseCaseInteractor extends Interactor<UseCase> {
+    async create(
+        props: Omit<In, 'id'>
+    ): Promise<Uuid> {
+        return await this.repository.add(new UseCase({
+            id: crypto.randomUUID(),
+            extensions: props.extensions,
+            goalInContext: props.goalInContext,
+            level: props.level,
+            mainSuccessScenario: props.mainSuccessScenario,
+            name: props.name,
+            parentId: props.parentId,
+            preCondition: props.preCondition,
+            primaryActorId: props.primaryActorId,
+            property: '',
+            scope: props.scope,
+            solutionId: props.solutionId,
+            stakeHoldersAndInterests: props.stakeHoldersAndInterests,
+            successGuarantee: props.successGuarantee,
+            statement: '',
+            trigger: props.trigger
+        }))
+    }
+
+    async delete(id: Uuid): Promise<void> {
+        await this.repository.delete(id)
+    }
+
+    async getAll(solutionId: Uuid): Promise<UseCase[]> {
+        return await this.repository.getAll(
+            useCase => useCase.solutionId === solutionId
+        )
+    }
+
+    async update(props: In): Promise<void> {
+        await this.repository.update(new UseCase({
+            id: props.id,
+            extensions: props.extensions,
+            goalInContext: props.goalInContext,
+            level: props.level,
+            mainSuccessScenario: props.mainSuccessScenario,
+            name: props.name,
+            parentId: props.parentId,
+            preCondition: props.preCondition,
+            primaryActorId: props.primaryActorId,
+            property: '',
+            scope: props.scope,
+            solutionId: props.solutionId,
+            stakeHoldersAndInterests: props.stakeHoldersAndInterests,
+            successGuarantee: props.successGuarantee,
+            statement: '',
+            trigger: props.trigger
+        }))
+    }
+}
\ No newline at end of file
diff --git a/modules/system/domain/TestCase.ts b/modules/system/domain/TestCase.ts
index fad344d4..2909903b 100644
--- a/modules/system/domain/TestCase.ts
+++ b/modules/system/domain/TestCase.ts
@@ -1,3 +1,8 @@
 import Example from "./Example";
 
+/**
+ * A TestCase is a specification of the inputs, execution conditions, 
+ * testing procedure, and expected results that define a single test to
+ * be executed to achieve a particular goal.,
+ */
 export default class TestCase extends Example { }
\ No newline at end of file
diff --git a/modules/system/domain/UseCase.ts b/modules/system/domain/UseCase.ts
index d39a3b94..8b9bacdf 100644
--- a/modules/system/domain/UseCase.ts
+++ b/modules/system/domain/UseCase.ts
@@ -1,7 +1,73 @@
 import Scenario from "./Scenario";
+import type { Uuid } from "~/domain/Uuid";
+import type { Properties } from "~/domain/Properties";
 
 /**
  * A Use Case specifies the scenario of a complete 
  * interaction of a user through a system.
  */
-export default class UseCase extends Scenario { }
\ No newline at end of file
+export default class UseCase extends Scenario {
+    /**
+     * TODO: <https://github.com/final-hill/cathedral/issues/154>
+     */
+    scope: string
+
+    /**
+     * TODO: <https://github.com/final-hill/cathedral/issues/154>
+     */
+    level: string
+
+    /**
+     * TODO: is this just the Goal.description?
+     */
+    goalInContext: string
+
+    /**
+     * The preCondition is an Assumption that must be true before the use case can start.
+     */
+    preCondition: Uuid
+
+    // the action upon the system that starts the use case
+    // A Responsibility? Functional Requirement?
+    trigger: Uuid
+
+    /**
+     * The main success scenario is the most common path through the system.
+     * It takes the form of a sequence of steps that describe the interaction:
+     * 1. The use case starts when <Actor> <does something>.
+     * 2. The system <does something in response>.
+     * 3. The <Actor name> does something else.
+     * ...
+     */
+    //mainSuccessScenario: [FunctionalRequirement | Constraint | Role | Responsibility][]
+    mainSuccessScenario: string
+
+    /**
+     * An Effect that is guaranteed to be true after the use case is completed.
+     */
+    successGuarantee: Uuid
+
+    /**
+     * 
+     */
+    // extensions: [FunctionalRequirement | Constraint | Role | Responsibility][]
+    extensions: string
+
+    /**
+     * 
+     */
+    stakeHoldersAndInterests: Uuid[] // Actor[]
+
+    constructor(props: Properties<UseCase>) {
+        super(props)
+        this.scope = props.scope
+        this.level = props.level
+        this.goalInContext = props.goalInContext
+        this.preCondition = props.preCondition
+        this.trigger = props.trigger
+        this.mainSuccessScenario = props.mainSuccessScenario
+        this.successGuarantee = props.successGuarantee
+        this.extensions = props.extensions
+        this.stakeHoldersAndInterests = props.stakeHoldersAndInterests
+    }
+}
\ No newline at end of file
diff --git a/modules/system/mappers/UseCaseToJsonMapper.ts b/modules/system/mappers/UseCaseToJsonMapper.ts
index e72f4872..f34ab4f2 100644
--- a/modules/system/mappers/UseCaseToJsonMapper.ts
+++ b/modules/system/mappers/UseCaseToJsonMapper.ts
@@ -1,7 +1,18 @@
 import ScenarioToJsonMapper, { type ScenarioJson } from "./ScenarioToJsonMapper";
 import UseCase from "../domain/UseCase";
+import type { Uuid } from "~/domain/Uuid";
 
-export interface UseCaseJson extends ScenarioJson { }
+export interface UseCaseJson extends ScenarioJson {
+    scope: string
+    level: string
+    goalInContext: string
+    preCondition: Uuid
+    trigger: Uuid
+    mainSuccessScenario: string
+    successGuarantee: Uuid
+    extensions: string
+    stakeHoldersAndInterests: Uuid[]
+}
 
 export default class UseCaseToJsonMapper extends ScenarioToJsonMapper {
     override mapFrom(target: UseCaseJson): UseCase {
@@ -10,7 +21,16 @@ export default class UseCaseToJsonMapper extends ScenarioToJsonMapper {
 
     override mapTo(source: UseCase): UseCaseJson {
         return {
-            ...super.mapTo(source)
+            ...super.mapTo(source),
+            scope: source.scope,
+            level: source.level,
+            goalInContext: source.goalInContext,
+            preCondition: source.preCondition,
+            trigger: source.trigger,
+            mainSuccessScenario: source.mainSuccessScenario,
+            successGuarantee: source.successGuarantee,
+            extensions: source.extensions,
+            stakeHoldersAndInterests: source.stakeHoldersAndInterests
         };
     }
 }
\ No newline at end of file
diff --git a/modules/system/ui/pages/Scenarios.vue b/modules/system/ui/pages/Scenarios.vue
index 3d57f0f8..e9f4c1c3 100644
--- a/modules/system/ui/pages/Scenarios.vue
+++ b/modules/system/ui/pages/Scenarios.vue
@@ -6,6 +6,7 @@ import UserStoryInteractor from '../../application/UserStoryInteractor';
 import GetSolutionBySlugUseCase from '~/modules/solution/application/GetSolutionBySlugUseCase';
 import GetSystemBySolutionIdUseCase from '../../application/GetSystemBySolutionIdUseCase';
 import type UserStory from '../../domain/UserStory';
+import type UseCase from '../../domain/UseCase';
 import { emptyUuid, type Uuid } from '~/domain/Uuid';
 import { FilterMatchMode } from 'primevue/api';
 import EpicRepository from '~/modules/goals/data/EpicRepository';
@@ -19,6 +20,9 @@ import StakeholderRepository from '~/modules/goals/data/StakeholderRepository';
 import GetStakeHoldersUseCase from '~/modules/goals/application/GetStakeHoldersUseCase';
 import Stakeholder from '~/modules/goals/domain/Stakeholder';
 import EpicInteractor from '~/modules/goals/application/EpicInteractor';
+import type { Properties } from '~/domain/Properties';
+import UseCaseInteractor from '../../application/UseCaseInteractor';
+import UseCaseRepository from '../../data/UseCaseRepository';
 
 useHead({
     title: 'Scenarios'
@@ -32,6 +36,7 @@ const router = useRouter(),
     userStoryRepository = new UserStoryRepository(),
     goalsRepository = new GoalsRepository(),
     epicRepository = new EpicRepository(),
+    useCaseRepository = new UseCaseRepository(),
     stakeholderRepository = new StakeholderRepository(),
     functionalRequirementsRepository = new FunctionalRequirementRepository(),
     userStoryInteractor = new UserStoryInteractor(userStoryRepository),
@@ -41,6 +46,7 @@ const router = useRouter(),
     getGoalsBySolutionIdUseCase = new GetGoalsBySolutionIdUseCase(goalsRepository),
     functionalRequirementInteractor = new FunctionalRequirementInteractor(functionalRequirementsRepository),
     epicInteractor = new EpicInteractor(epicRepository),
+    useCaseInteractor = new UseCaseInteractor(useCaseRepository),
     getStakeholdersUseCase = new GetStakeHoldersUseCase(stakeholderRepository),
     system = solution?.id && await getSystemBySolutionIdUseCase.execute(solution.id),
     goals = solution?.id && await getGoalsBySolutionIdUseCase.execute(solution.id)
@@ -54,7 +60,10 @@ if (!solution) {
 
 type UserStoryViewModel = Pick<UserStory, 'id' | 'name' | 'primaryActorId' | 'behaviorId' | 'epicId'>
 
+type UseCaseViewModel = Pick<UseCase, 'id' | 'name' | 'primaryActorId' | 'extensions' | 'goalInContext' | 'level' | 'mainSuccessScenario' | 'preCondition' | 'scope' | 'stakeHoldersAndInterests' | 'successGuarantee' | 'trigger'>
+
 const userStories = ref<UserStoryViewModel[]>([]),
+    useCases = ref<UseCaseViewModel[]>([]),
     emptyUserStory: UserStoryViewModel = {
         id: emptyUuid,
         name: '',
@@ -62,6 +71,20 @@ const userStories = ref<UserStoryViewModel[]>([]),
         behaviorId: emptyUuid,
         epicId: emptyUuid
     },
+    emptyUseCase: UseCaseViewModel = {
+        id: emptyUuid,
+        name: '',
+        primaryActorId: emptyUuid,
+        extensions: '',
+        goalInContext: '',
+        level: '',
+        mainSuccessScenario: '',
+        preCondition: emptyUuid,
+        scope: '',
+        stakeHoldersAndInterests: [],
+        successGuarantee: emptyUuid,
+        trigger: emptyUuid
+    },
     roles = ref<Stakeholder[]>([]),
     behaviors = ref<FunctionalRequirement[]>([]),
     epics = ref<Epic[]>([]);
@@ -71,16 +94,31 @@ onMounted(async () => {
     roles.value = await getStakeholdersUseCase.execute(goals!.id);
     behaviors.value = await functionalRequirementInteractor.getAll(solution!.id);
     epics.value = await epicInteractor.getAll(solution!.id);
+    useCases.value = await useCaseInteractor.getAll(solution!.id);
 })
 
-const filters = ref({
+const userStoryfilters = ref({
     'name': { value: null, matchMode: FilterMatchMode.CONTAINS },
     'primaryActorId': { value: null, matchMode: FilterMatchMode.EQUALS },
     'behaviorId': { value: null, matchMode: FilterMatchMode.EQUALS },
     'epicId': { value: null, matchMode: FilterMatchMode.EQUALS }
 })
 
-const onCreate = async (userStory: UserStoryViewModel) => {
+const useCasefilters = ref({
+    'name': { value: null, matchMode: FilterMatchMode.CONTAINS },
+    'primaryActorId': { value: null, matchMode: FilterMatchMode.EQUALS },
+    'extensions': { value: null, matchMode: FilterMatchMode.CONTAINS },
+    'goalInContext': { value: null, matchMode: FilterMatchMode.CONTAINS },
+    'level': { value: null, matchMode: FilterMatchMode.CONTAINS },
+    'mainSuccessScenario': { value: null, matchMode: FilterMatchMode.CONTAINS },
+    'preCondition': { value: null, matchMode: FilterMatchMode.EQUALS },
+    'scope': { value: null, matchMode: FilterMatchMode.CONTAINS },
+    'stakeHoldersAndInterests': { value: null, matchMode: FilterMatchMode.CONTAINS },
+    'successGuarantee': { value: null, matchMode: FilterMatchMode.EQUALS },
+    'trigger': { value: null, matchMode: FilterMatchMode.EQUALS }
+})
+
+const onUserStoryCreate = async (userStory: UserStoryViewModel) => {
     const newId = await userStoryInteractor.create({
         ...userStory,
         solutionId: solution!.id,
@@ -90,7 +128,17 @@ const onCreate = async (userStory: UserStoryViewModel) => {
     userStories.value = await userStoryInteractor.getAll(system!.id);
 }
 
-const onUpdate = async (userStory: UserStoryViewModel) => {
+const onUseCaseCreate = async (useCase: UseCaseViewModel) => {
+    const newId = await useCaseInteractor.create({
+        ...useCase,
+        solutionId: solution!.id,
+        parentId: system!.id
+    });
+
+    useCases.value = await useCaseInteractor.getAll(system!.id);
+}
+
+const onUserStoryUpdate = async (userStory: UserStoryViewModel) => {
     await userStoryInteractor.update({
         ...userStory,
         parentId: system!.id,
@@ -100,11 +148,27 @@ const onUpdate = async (userStory: UserStoryViewModel) => {
     userStories.value = await userStoryInteractor.getAll(system!.id);
 }
 
-const onDelete = async (id: Uuid) => {
+const onUseCaseUpdate = async (useCase: UseCaseViewModel) => {
+    await useCaseInteractor.update({
+        ...useCase,
+        parentId: system!.id,
+        solutionId: solution!.id
+    });
+
+    useCases.value = await useCaseInteractor.getAll(system!.id);
+}
+
+const onUserStoryDelete = async (id: Uuid) => {
     await userStoryInteractor.delete(id);
 
     userStories.value = await userStoryInteractor.getAll(system!.id);
 }
+
+const onUseCaseDelete = async (id: Uuid) => {
+    await useCaseInteractor.delete(id);
+
+    useCases.value = await useCaseInteractor.getAll(system!.id);
+}
 </script>
 
 <template>
@@ -119,8 +183,8 @@ const onDelete = async (id: Uuid) => {
                 leveraging a particular behavior of the system.
             </p>
 
-            <XDataTable :datasource="userStories" :filters="filters" :emptyRecord="emptyUserStory" :onCreate="onCreate"
-                :onUpdate="onUpdate" :onDelete="onDelete">
+            <XDataTable :datasource="userStories" :filters="userStoryfilters" :emptyRecord="emptyUserStory"
+                :onCreate="onUserStoryCreate" :onUpdate="onUserStoryUpdate" :onDelete="onUserStoryDelete">
                 <Column field="name" header="Name" sortable>
                     <template #filter="{ filterModel, filterCallback }">
                         <InputText v-model.trim="filterModel.value" @input="filterCallback()"
@@ -176,8 +240,141 @@ const onDelete = async (id: Uuid) => {
         </TabPanel>
         <TabPanel header="Use Cases">
             <p>
-                Use Cases
+                A Use Case describes a complete interaction between an actor and the
+                system to achieve a goal.
             </p>
+            <XDataTable :datasource="useCases" :filters="useCasefilters" :emptyRecord="emptyUseCase"
+                :onCreate="onUseCaseCreate" :onUpdate="onUseCaseUpdate" :onDelete="onUseCaseDelete">
+                <Column field="name" header="Name" sortable>
+                    <template #filter="{ filterModel, filterCallback }">
+                        <InputText v-model.trim="filterModel.value" @input="filterCallback()"
+                            placeholder="Search by name" />
+                    </template>
+                    <template #body="{ data, field }">
+                        {{ data[field] }}
+                    </template>
+                    <template #editor="{ data, field }">
+                        <InputText v-model.trim="data[field]" required="true" placeholder="Enter a name" />
+                    </template>
+                </Column>
+                <Column field="scope" header="Scope">
+                    <template #filter="{ filterModel, filterCallback }">
+                        <InputText v-model.trim="filterModel.value" @input="filterCallback()"
+                            placeholder="Search by scope" />
+                    </template>
+                    <template #body="{ data, field }">
+                        {{ data[field] }}
+                    </template>
+                    <template #editor="{ data, field }">
+                        <InputText v-model.trim="data[field]" required="true" placeholder="Enter a scope" />
+                    </template>
+                </Column>
+                <Column field="level" header="Level">
+                    <template #filter="{ filterModel, filterCallback }">
+                        <InputText v-model.trim="filterModel.value" @input="filterCallback()"
+                            placeholder="Search by level" />
+                    </template>
+                    <template #body="{ data, field }">
+                        {{ data[field] }}
+                    </template>
+                    <template #editor="{ data, field }">
+                        <InputText v-model.trim="data[field]" required="true" placeholder="Enter a level" />
+                    </template>
+                </Column>
+                <Column field="primaryActorId" header="Primary Actor">
+                    <template #filter="{ filterModel, filterCallback }">
+                        <Dropdown v-model.trim="filterModel.value" @input="filterCallback()" optionLabel="name"
+                            optionValue="id" :options="roles" placeholder="Search by Actor" />
+                    </template>
+                    <template #body="{ data, field }">
+                        {{ roles.find(r => r.id === data[field])?.name }}
+                    </template>
+                    <template #editor="{ data, field }">
+                        <Dropdown v-model.trim="data[field]" optionLabel="name" optionValue="id" :options="roles"
+                            placeholder="Select an Actor" />
+                    </template>
+                </Column>
+                <Column field="goalInContext" header="Goal in Context">
+                    <template #filter="{ filterModel, filterCallback }">
+                        <InputText v-model.trim="filterModel.value" @input="filterCallback()"
+                            placeholder="Search by goal in context" />
+                    </template>
+                    <template #body="{ data, field }">
+                        {{ data[field] }}
+                    </template>
+                    <template #editor="{ data, field }">
+                        <InputText v-model.trim="data[field]" required="true" placeholder="Enter a goal in context" />
+                    </template>
+                </Column>
+                <Column field="preCondition" header="Pre-Condition">
+                    <template #filter="{ filterModel, filterCallback }">
+                        <Dropdown v-model.trim="filterModel.value" @input="filterCallback()" optionLabel="name"
+                            optionValue="id" :options="behaviors" placeholder="Search by pre-condition" />
+                    </template>
+                    <template #body="{ data, field }">
+                        {{ behaviors.find(b => b.id === data[field])?.name }}
+                    </template>
+                    <template #editor="{ data, field }">
+                        <Dropdown v-model.trim="data[field]" optionLabel="name" optionValue="id" :options="behaviors"
+                            placeholder="Select a pre-condition" />
+                    </template>
+                </Column>
+                <Column field="trigger" header="Trigger">
+                    <template #filter="{ filterModel, filterCallback }">
+                        <Dropdown v-model.trim="filterModel.value" @input="filterCallback()" optionLabel="name"
+                            optionValue="id" :options="behaviors" placeholder="Search by trigger" />
+                    </template>
+                    <template #body="{ data, field }">
+                        {{ behaviors.find(b => b.id === data[field])?.name }}
+                    </template>
+                    <template #editor="{ data, field }">
+                        <Dropdown v-model.trim="data[field]" optionLabel="name" optionValue="id" :options="behaviors"
+                            placeholder="Select a trigger" />
+                    </template>
+                </Column>
+                <Column field="mainSuccessScenario" header="Main Success Scenario">
+                    <template #body="{ data, field }">
+                        {{ data[field] }}
+                    </template>
+                    <template #editor="{ data, field }">
+                        <Textarea v-model.trim="data[field]" required="true" placeholder="Enter a main success scenario"
+                            rows="5" cols="30" />
+                    </template>
+                </Column>
+                <Column field="successGuarantee" header="Success Guarantee">
+                    <template #filter="{ filterModel, filterCallback }">
+                        <Dropdown v-model.trim="filterModel.value" @input="filterCallback()" optionLabel="name"
+                            optionValue="id" :options="behaviors" placeholder="Search by success guarantee" />
+                    </template>
+                    <template #body="{ data, field }">
+                        {{ behaviors.find(b => b.id === data[field])?.name }}
+                    </template>
+                    <template #editor="{ data, field }">
+                        <Dropdown v-model.trim="data[field]" optionLabel="name" optionValue="id" :options="behaviors"
+                            placeholder="Select a success guarantee" />
+                    </template>
+                </Column>
+                <Column field="extensions" header="Extensions">
+                    <template #body="{ data, field }">
+                        {{ data[field] }}
+                    </template>
+                    <template #editor="{ data, field }">
+                        <Textarea v-model.trim="data[field]" required="true" placeholder="Enter extensions" rows="5"
+                            cols="30" />
+                    </template>
+                </Column>
+                <Column field="stakeHoldersAndInterests" header="Stakeholders and Interests">
+                    <template #body="{ data, field }">
+                        {{
+                            data[field].map((id: Uuid) => roles.find((r: any) => r.id === id)?.name).join(', ')
+                        }}
+                    </template>
+                    <template #editor="{ data, field }">
+                        <Listbox v-model.trim="data[field]" :options="roles" optionLabel="name" filter multiple
+                            checkmark />
+                    </template>
+                </Column>
+            </XDataTable>
         </TabPanel>
     </TabView>
 </template>
\ No newline at end of file