diff --git a/backend/LexBoxApi/GraphQL/ProjectMutations.cs b/backend/LexBoxApi/GraphQL/ProjectMutations.cs
index f2e11e9b8..e6e01ec5d 100644
--- a/backend/LexBoxApi/GraphQL/ProjectMutations.cs
+++ b/backend/LexBoxApi/GraphQL/ProjectMutations.cs
@@ -285,6 +285,27 @@ public async Task<IQueryable<Project>> SetProjectConfidentiality(SetProjectConfi
         return dbContext.Projects.Where(p => p.Id == input.ProjectId);
     }
 
+    [Error<NotFoundException>]
+    [Error<DbError>]
+    [UseMutationConvention]
+    [UseFirstOrDefault]
+    [UseProjection]
+    public async Task<IQueryable<Project>> SetRetentionPolicy(
+        SetRetentionPolicyInput input,
+        IPermissionService permissionService,
+        [Service] ProjectService projectService,
+        LexBoxDbContext dbContext)
+    {
+        await permissionService.AssertCanManageProject(input.ProjectId);
+        var project = await dbContext.Projects.FindAsync(input.ProjectId);
+        NotFoundException.ThrowIfNull(project);
+
+        project.RetentionPolicy = input.RetentionPolicy;
+        project.UpdateUpdatedDate();
+        await dbContext.SaveChangesAsync();
+        return dbContext.Projects.Where(p => p.Id == input.ProjectId);
+    }
+
     [Error<NotFoundException>]
     [Error<LastMemberCantLeaveException>]
     [UseMutationConvention]
diff --git a/backend/LexBoxApi/Models/Project/ChangeProjectInputs.cs b/backend/LexBoxApi/Models/Project/ChangeProjectInputs.cs
index d6fed8c71..f0dd80786 100644
--- a/backend/LexBoxApi/Models/Project/ChangeProjectInputs.cs
+++ b/backend/LexBoxApi/Models/Project/ChangeProjectInputs.cs
@@ -1,3 +1,5 @@
+using LexCore.Entities;
+
 namespace LexBoxApi.Models.Project;
 
 public record ChangeProjectNameInput(Guid ProjectId, string Name);
@@ -6,6 +8,8 @@ public record ChangeProjectDescriptionInput(Guid ProjectId, string Description);
 
 public record SetProjectConfidentialityInput(Guid ProjectId, bool IsConfidential);
 
+public record SetRetentionPolicyInput(Guid ProjectId, RetentionPolicy RetentionPolicy);
+
 public record DeleteUserByAdminOrSelfInput(Guid UserId);
 
 public record ResetProjectByAdminInput(string Code);
diff --git a/frontend/schema.graphql b/frontend/schema.graphql
index 946d97f73..fd54a402f 100644
--- a/frontend/schema.graphql
+++ b/frontend/schema.graphql
@@ -236,6 +236,7 @@ type Mutation {
   changeProjectName(input: ChangeProjectNameInput!): ChangeProjectNamePayload!
   changeProjectDescription(input: ChangeProjectDescriptionInput!): ChangeProjectDescriptionPayload!
   setProjectConfidentiality(input: SetProjectConfidentialityInput!): SetProjectConfidentialityPayload!
+  setRetentionPolicy(input: SetRetentionPolicyInput!): SetRetentionPolicyPayload!
   leaveProject(input: LeaveProjectInput!): LeaveProjectPayload!
   removeProjectMember(input: RemoveProjectMemberInput!): RemoveProjectMemberPayload!
   deleteDraftProject(input: DeleteDraftProjectInput!): DeleteDraftProjectPayload! @authorize(policy: "AdminRequiredPolicy")
@@ -442,6 +443,11 @@ type SetProjectConfidentialityPayload {
   errors: [SetProjectConfidentialityError!]
 }
 
+type SetRetentionPolicyPayload {
+  project: Project
+  errors: [SetRetentionPolicyError!]
+}
+
 type SetUserLockedPayload {
   user: User
   errors: [SetUserLockedError!]
@@ -538,6 +544,8 @@ union SetOrgMemberRoleError = DbError | NotFoundError | OrgMemberInvitedByEmail
 
 union SetProjectConfidentialityError = NotFoundError | DbError
 
+union SetRetentionPolicyError = NotFoundError | DbError
+
 union SetUserLockedError = NotFoundError
 
 union SoftDeleteProjectError = NotFoundError | DbError
@@ -943,6 +951,11 @@ input SetProjectConfidentialityInput {
   isConfidential: Boolean!
 }
 
+input SetRetentionPolicyInput {
+  projectId: UUID!
+  retentionPolicy: RetentionPolicy!
+}
+
 input SetUserLockedInput {
   userId: UUID!
   locked: Boolean!
diff --git a/frontend/src/lib/components/modals/FormModal.svelte b/frontend/src/lib/components/modals/FormModal.svelte
index e9e51f7bf..071b986f1 100644
--- a/frontend/src/lib/components/modals/FormModal.svelte
+++ b/frontend/src/lib/components/modals/FormModal.svelte
@@ -57,12 +57,12 @@
     const response = await openModal(onSubmit);
     const _formState = $formState; // we need to read the form state before the modal closes or it will be reset
     if (response !== DialogResponse.Submit || !options?.keepOpenOnSubmit)
-      modal.close();
+      modal?.close();
     return { response, formState: _formState };
   }
 
   export function close(): void {
-    modal.close();
+    modal?.close();
   }
 
   export function form(): Readable<FormType> {
diff --git a/frontend/src/lib/i18n/locales/en.json b/frontend/src/lib/i18n/locales/en.json
index caedf6a73..3778e28fa 100644
--- a/frontend/src/lib/i18n/locales/en.json
+++ b/frontend/src/lib/i18n/locales/en.json
@@ -430,6 +430,11 @@ the [Linguistics Institute at Payap University](https://li.payap.ac.th/) in Chia
       "author_header": "Author",
       "log_header": "Message"
     },
+    "add_purpose": {
+      "add_button": "Add Purpose",
+      "modal_title": "Choose purpose",
+      "notify_success": "You have successfully added a project purpose."
+    },
     "get_project": {
       "instructions_header": "To {isEmpty, select, true { set up } other { get } } this project with {type, select, FL_EX { FLEx } WE_SAY { WeSay } other { (e.g.) FLEx } } {mode, select, manual { manually} other { }}",
       "instructions_flex": "1. In the \"Send/Receive\" menu click \"Get Project from colleague…\"\n\
diff --git a/frontend/src/routes/(authenticated)/project/[project_code]/+page.svelte b/frontend/src/routes/(authenticated)/project/[project_code]/+page.svelte
index ecd9ef8de..98699793a 100644
--- a/frontend/src/routes/(authenticated)/project/[project_code]/+page.svelte
+++ b/frontend/src/routes/(authenticated)/project/[project_code]/+page.svelte
@@ -29,7 +29,7 @@
   import MoreSettings from '$lib/components/MoreSettings.svelte';
   import { AdminContent, PageBreadcrumb } from '$lib/layout';
   import Markdown from 'svelte-exmarkdown';
-  import { OrgRole, ProjectRole, ProjectType, ResetStatus } from '$lib/gql/generated/graphql';
+  import { OrgRole, ProjectRole, ProjectType, ResetStatus, RetentionPolicy } from '$lib/gql/generated/graphql';
   import Icon from '$lib/icons/Icon.svelte';
   import OpenInFlexModal from './OpenInFlexModal.svelte';
   import OpenInFlexButton from './OpenInFlexButton.svelte';
@@ -45,6 +45,7 @@
   import DetailsPage from '$lib/layout/DetailsPage.svelte';
   import OrgList from './OrgList.svelte';
   import AddOrganization from './AddOrganization.svelte';
+  import AddPurpose from './AddPurpose.svelte';
   import WritingSystemList from '$lib/components/Projects/WritingSystemList.svelte';
 
   export let data: PageData;
@@ -306,9 +307,15 @@
       <BadgeList>
         <ProjectConfidentialityBadge on:click={projectConfidentialityModal.openModal} {canManage} isConfidential={project.isConfidential ?? undefined} />
         <ProjectTypeBadge type={project.type} />
-        <Badge>
-          <FormatRetentionPolicy policy={project.retentionPolicy} />
-        </Badge>
+        {#if project.retentionPolicy === RetentionPolicy.Unknown}
+          {#if canManage}
+            <AddPurpose projectId={project.id} />
+          {/if}
+        {:else}
+          <Badge>
+            <FormatRetentionPolicy policy={project.retentionPolicy} />
+          </Badge>
+        {/if}
         {#if project.resetStatus === ResetStatus.InProgress}
           <button
             class:tooltip={user.isAdmin}
@@ -384,9 +391,7 @@
     </svelte:fragment>
 
     <div class="space-y-4">
-      <OrgList
-        organizations={project.organizations}
-      >
+      <OrgList organizations={project.organizations} >
         <svelte:fragment slot="extraButtons">
           {#if canManage}
             <AddOrganization projectId={project.id} userIsAdmin={user.isAdmin} />
diff --git a/frontend/src/routes/(authenticated)/project/[project_code]/+page.ts b/frontend/src/routes/(authenticated)/project/[project_code]/+page.ts
index 54d925cab..8f5efda05 100644
--- a/frontend/src/routes/(authenticated)/project/[project_code]/+page.ts
+++ b/frontend/src/routes/(authenticated)/project/[project_code]/+page.ts
@@ -18,6 +18,8 @@ import type {
   ProjectPageQuery,
   SetProjectConfidentialityInput,
   SetProjectConfidentialityMutation,
+  SetRetentionPolicyInput,
+  SetRetentionPolicyMutation,
 } from '$lib/gql/types';
 import { getClient, graphql } from '$lib/gql';
 
@@ -368,6 +370,30 @@ export async function _setProjectConfidentiality(input: SetProjectConfidentialit
   return result;
 }
 
+export async function _setRetentionPolicy(input: SetRetentionPolicyInput): $OpResult<SetRetentionPolicyMutation> {
+  //language=GraphQL
+  const result = await getClient()
+    .mutation(
+      graphql(`
+        mutation SetRetentionPolicy($input: SetRetentionPolicyInput!) {
+          setRetentionPolicy(input: $input) {
+            project {
+              id
+              retentionPolicy
+            }
+            errors {
+              ... on Error {
+                message
+              }
+            }
+          }
+        }
+      `),
+      { input: input }
+    );
+  return result;
+}
+
 export async function _deleteProjectUser(projectId: string, userId: string): $OpResult<DeleteProjectUserMutation> {
   const result = await getClient()
     .mutation(
diff --git a/frontend/src/routes/(authenticated)/project/[project_code]/AddPurpose.svelte b/frontend/src/routes/(authenticated)/project/[project_code]/AddPurpose.svelte
new file mode 100644
index 000000000..d3ef12a54
--- /dev/null
+++ b/frontend/src/routes/(authenticated)/project/[project_code]/AddPurpose.svelte
@@ -0,0 +1,61 @@
+<script lang="ts">
+  import { z } from 'zod';
+  import t from '$lib/i18n';
+  import { useNotifications } from '$lib/notify';
+  import { BadgeButton } from '$lib/components/Badges';
+  import { Select } from '$lib/forms';
+  import { AdminContent } from '$lib/layout';
+  import { RetentionPolicy } from '$lib/gql/types';
+  import { _setRetentionPolicy } from './+page';
+  import { DialogResponse, FormModal } from '$lib/components/modals';
+
+  export let projectId: string;
+
+  const schema = z.object({
+    retentionPolicy: z.nativeEnum(RetentionPolicy).default(RetentionPolicy.Training)
+  });
+
+  type Schema = typeof schema;
+  let formModal: FormModal<Schema>;
+  $: form = formModal?.form();
+
+  const { notifySuccess } = useNotifications();
+
+  async function openModal(): Promise<void> {
+    const { response, formState } = await formModal.open(async () => {
+      const { error } = await _setRetentionPolicy({
+        projectId,
+        retentionPolicy: $form.retentionPolicy,
+      })
+      if (error?.byType('NotFoundError')) {
+        if (error.message === 'Project not found') return $t('project_page.add_org.project_not_found');
+      }
+    });
+
+    if (response === DialogResponse.Submit && formState.retentionPolicy.currentValue) {
+        notifySuccess($t('project_page.add_purpose.notify_success'));
+    }
+  }
+</script>
+
+<BadgeButton variant="badge-success" icon="i-mdi-plus" on:click={openModal}>
+  {$t('project_page.add_purpose.add_button')}
+</BadgeButton>
+
+<FormModal bind:this={formModal} {schema} let:errors>
+  <span slot="title">{$t('project_page.add_purpose.modal_title')}</span>
+  <Select
+    id="policy"
+    label={$t('project.create.retention_policy')}
+    bind:value={$form.retentionPolicy}
+    error={errors.retentionPolicy}
+  >
+    <option value={RetentionPolicy.Verified}>{$t('retention_policy.language_project')}</option>
+    <option value={RetentionPolicy.Training}>{$t('retention_policy.training')}</option>
+    <option value={RetentionPolicy.Test}>{$t('retention_policy.test')}</option>
+    <AdminContent>
+      <option value={RetentionPolicy.Dev}>{$t('retention_policy.dev')}</option>
+    </AdminContent>
+  </Select>
+  <span slot="submitText">{'Add Purpose'}</span>
+</FormModal>