diff --git a/components/projects/acceptance-criteria-editor.tsx b/components/projects/acceptance-criteria-editor.tsx
new file mode 100644
index 0000000..7637d12
--- /dev/null
+++ b/components/projects/acceptance-criteria-editor.tsx
@@ -0,0 +1,96 @@
+'use client';
+
+import { useState } from 'react';
+import { Button } from '@/components/ui/button';
+import { Input } from '@/components/ui/input';
+import { Checkbox } from '@/components/ui/checkbox';
+import { X, Plus } from 'lucide-react';
+
+interface AcceptanceCriteriaEditorProps {
+  criteria: string[];
+  onChange: (criteria: string[]) => void;
+  disabled?: boolean;
+}
+
+export function AcceptanceCriteriaEditor({
+  criteria,
+  onChange,
+  disabled,
+}: AcceptanceCriteriaEditorProps) {
+  const [newCriterion, setNewCriterion] = useState('');
+
+  const addCriterion = () => {
+    if (newCriterion.trim()) {
+      onChange([...criteria, newCriterion.trim()]);
+      setNewCriterion('');
+    }
+  };
+
+  const removeCriterion = (index: number) => {
+    onChange(criteria.filter((_, i) => i !== index));
+  };
+
+  const handleKeyPress = (e: React.KeyboardEvent) => {
+    if (e.key === 'Enter') {
+      e.preventDefault();
+      addCriterion();
+    }
+  };
+
+  return (
+    <div className="space-y-3">
+      {/* Existing criteria list */}
+      {criteria.length > 0 && (
+        <div className="space-y-2">
+          {criteria.map((criterion, index) => (
+            <div
+              key={index}
+              className="flex items-start gap-2 p-2 rounded-md border bg-muted/50"
+            >
+              <Checkbox checked disabled className="mt-0.5" />
+              <span className="flex-1 text-sm">{criterion}</span>
+              {!disabled && (
+                <Button
+                  type="button"
+                  variant="ghost"
+                  size="sm"
+                  className="h-6 w-6 p-0"
+                  onClick={() => removeCriterion(index)}
+                >
+                  <X className="h-3 w-3" />
+                </Button>
+              )}
+            </div>
+          ))}
+        </div>
+      )}
+
+      {/* Add new criterion */}
+      {!disabled && (
+        <div className="flex gap-2">
+          <Input
+            placeholder="Add acceptance criterion..."
+            value={newCriterion}
+            onChange={(e) => setNewCriterion(e.target.value)}
+            onKeyPress={handleKeyPress}
+          />
+          <Button
+            type="button"
+            variant="outline"
+            size="sm"
+            onClick={addCriterion}
+            disabled={!newCriterion.trim()}
+          >
+            <Plus className="h-4 w-4" />
+          </Button>
+        </div>
+      )}
+
+      {criteria.length === 0 && disabled && (
+        <p className="text-sm text-muted-foreground">
+          No acceptance criteria defined
+        </p>
+      )}
+    </div>
+  );
+}
diff --git a/components/projects/story-form.tsx b/components/projects/story-form.tsx
index 2c7837c..e5a6456 100644
--- a/components/projects/story-form.tsx
+++ b/components/projects/story-form.tsx
@@ -28,6 +28,8 @@ import type { Story, WorkItemPriority } from '@/types/project';
 import { toast } from 'sonner';
 import { Loader2 } from 'lucide-react';
 import { useAuthStore } from '@/stores/authStore';
+import { AcceptanceCriteriaEditor } from './acceptance-criteria-editor';
+import { TagsInput } from './tags-input';
 
 const storySchema = z.object({
   epicId: z.string().min(1, 'Parent Epic is required'),
@@ -45,6 +47,16 @@ const storySchema = z.object({
     .min(0, 'Estimated hours must be positive')
     .optional()
     .or(z.literal('')),
+  // Sprint 4 Story 3: New fields
+  acceptanceCriteria: z.array(z.string()).default([]),
+  assigneeId: z.string().optional(),
+  tags: z.array(z.string()).default([]),
+  storyPoints: z
+    .number()
+    .min(0, 'Story points must be positive')
+    .max(100, 'Story points must be less than 100')
+    .optional()
+    .or(z.literal('')),
 });
 
 type StoryFormValues = z.infer<typeof storySchema>;
@@ -80,6 +92,11 @@ export function StoryForm({
       description: story?.description || '',
       priority: story?.priority || 'Medium',
       estimatedHours: story?.estimatedHours || ('' as any),
+      // Sprint 4 Story 3: New field defaults
+      acceptanceCriteria: story?.acceptanceCriteria || [],
+      assigneeId: story?.assigneeId || '',
+      tags: story?.tags || [],
+      storyPoints: story?.storyPoints || ('' as any),
     },
   });
 
@@ -94,6 +111,12 @@ export function StoryForm({
             priority: data.priority,
             estimatedHours:
               typeof data.estimatedHours === 'number' ? data.estimatedHours : undefined,
+            // Sprint 4 Story 3: New fields
+            acceptanceCriteria: data.acceptanceCriteria,
+            assigneeId: data.assigneeId || undefined,
+            tags: data.tags,
+            storyPoints:
+              typeof data.storyPoints === 'number' ? data.storyPoints : undefined,
           },
         });
         toast.success('Story updated successfully');
@@ -115,6 +138,12 @@ export function StoryForm({
           estimatedHours:
             typeof data.estimatedHours === 'number' ? data.estimatedHours : undefined,
           createdBy: user.id,
+          // Sprint 4 Story 3: New fields
+          acceptanceCriteria: data.acceptanceCriteria,
+          assigneeId: data.assigneeId || undefined,
+          tags: data.tags,
+          storyPoints:
+            typeof data.storyPoints === 'number' ? data.storyPoints : undefined,
         });
         toast.success('Story created successfully');
       }
@@ -259,6 +288,111 @@ export function StoryForm({
           />
         </div>
 
+        {/* Sprint 4 Story 3: Acceptance Criteria */}
+        <FormField
+          control={form.control}
+          name="acceptanceCriteria"
+          render={({ field }) => (
+            <FormItem>
+              <FormLabel>Acceptance Criteria</FormLabel>
+              <FormControl>
+                <AcceptanceCriteriaEditor
+                  criteria={field.value}
+                  onChange={field.onChange}
+                  disabled={isLoading}
+                />
+              </FormControl>
+              <FormDescription>
+                Define conditions that must be met for this story to be complete
+              </FormDescription>
+              <FormMessage />
+            </FormItem>
+          )}
+        />
+
+        {/* Sprint 4 Story 3: Assignee and Story Points */}
+        <div className="grid grid-cols-2 gap-4">
+          <FormField
+            control={form.control}
+            name="assigneeId"
+            render={({ field }) => (
+              <FormItem>
+                <FormLabel>Assignee</FormLabel>
+                <Select
+                  onValueChange={field.onChange}
+                  value={field.value}
+                  disabled={isLoading}
+                >
+                  <FormControl>
+                    <SelectTrigger>
+                      <SelectValue placeholder="Unassigned" />
+                    </SelectTrigger>
+                  </FormControl>
+                  <SelectContent>
+                    <SelectItem value="">Unassigned</SelectItem>
+                    {user?.id && (
+                      <SelectItem value={user.id}>{user.fullName || 'Me'}</SelectItem>
+                    )}
+                  </SelectContent>
+                </Select>
+                <FormDescription>Assign to team member</FormDescription>
+                <FormMessage />
+              </FormItem>
+            )}
+          />
+
+          <FormField
+            control={form.control}
+            name="storyPoints"
+            render={({ field }) => (
+              <FormItem>
+                <FormLabel>Story Points</FormLabel>
+                <FormControl>
+                  <Input
+                    type="number"
+                    placeholder="e.g., 5"
+                    min="0"
+                    max="100"
+                    step="1"
+                    {...field}
+                    onChange={(e) => {
+                      const value = e.target.value;
+                      field.onChange(value === '' ? '' : parseInt(value));
+                    }}
+                    value={field.value === undefined ? '' : field.value}
+                    disabled={isLoading}
+                  />
+                </FormControl>
+                <FormDescription>Fibonacci: 1, 2, 3, 5, 8, 13...</FormDescription>
+                <FormMessage />
+              </FormItem>
+            )}
+          />
+        </div>
+
+        {/* Sprint 4 Story 3: Tags */}
+        <FormField
+          control={form.control}
+          name="tags"
+          render={({ field }) => (
+            <FormItem>
+              <FormLabel>Tags</FormLabel>
+              <FormControl>
+                <TagsInput
+                  tags={field.value}
+                  onChange={field.onChange}
+                  disabled={isLoading}
+                  placeholder="Add tags (press Enter)..."
+                />
+              </FormControl>
+              <FormDescription>
+                Add tags to categorize this story (e.g., frontend, bug, urgent)
+              </FormDescription>
+              <FormMessage />
+            </FormItem>
+          )}
+        />
+
         <div className="flex justify-end gap-3">
           {onCancel && (
             <Button
diff --git a/components/projects/tags-input.tsx b/components/projects/tags-input.tsx
new file mode 100644
index 0000000..e8314c5
--- /dev/null
+++ b/components/projects/tags-input.tsx
@@ -0,0 +1,78 @@
+'use client';
+
+import { useState } from 'react';
+import { Badge } from '@/components/ui/badge';
+import { Input } from '@/components/ui/input';
+import { X } from 'lucide-react';
+
+interface TagsInputProps {
+  tags: string[];
+  onChange: (tags: string[]) => void;
+  disabled?: boolean;
+  placeholder?: string;
+}
+
+export function TagsInput({
+  tags,
+  onChange,
+  disabled,
+  placeholder = 'Add tag and press Enter...',
+}: TagsInputProps) {
+  const [inputValue, setInputValue] = useState('');
+
+  const addTag = () => {
+    const tag = inputValue.trim().toLowerCase();
+    if (tag && !tags.includes(tag)) {
+      onChange([...tags, tag]);
+      setInputValue('');
+    }
+  };
+
+  const removeTag = (tagToRemove: string) => {
+    onChange(tags.filter((tag) => tag !== tagToRemove));
+  };
+
+  const handleKeyDown = (e: React.KeyboardEvent) => {
+    if (e.key === 'Enter') {
+      e.preventDefault();
+      addTag();
+    } else if (e.key === 'Backspace' && !inputValue && tags.length > 0) {
+      removeTag(tags[tags.length - 1]);
+    }
+  };
+
+  return (
+    <div className="space-y-2">
+      {/* Display existing tags */}
+      {tags.length > 0 && (
+        <div className="flex flex-wrap gap-2">
+          {tags.map((tag) => (
+            <Badge key={tag} variant="secondary" className="px-2 py-1">
+              {tag}
+              {!disabled && (
+                <button
+                  type="button"
+                  className="ml-1 hover:text-destructive"
+                  onClick={() => removeTag(tag)}
+                >
+                  <X className="h-3 w-3" />
+                </button>
+              )}
+            </Badge>
+          ))}
+        </div>
+      )}
+
+      {/* Input for new tags */}
+      {!disabled && (
+        <Input
+          placeholder={placeholder}
+          value={inputValue}
+          onChange={(e) => setInputValue(e.target.value)}
+          onKeyDown={handleKeyDown}
+          onBlur={() => inputValue && addTag()}
+        />
+      )}
+    </div>
+  );
+}
diff --git a/types/project.ts b/types/project.ts
index 707e180..393698c 100644
--- a/types/project.ts
+++ b/types/project.ts
@@ -71,6 +71,10 @@ export interface Story {
   estimatedHours?: number;
   actualHours?: number;
   assigneeId?: string;
+  assigneeName?: string;  // Sprint 4 Story 3: Assignee display name
+  acceptanceCriteria?: string[];  // Sprint 4 Story 3: Acceptance criteria list
+  tags?: string[];  // Sprint 4 Story 3: Tags/labels
+  storyPoints?: number;  // Sprint 4 Story 3: Story points
   tenantId: string;
   createdAt: string;
   updatedAt: string;
@@ -84,6 +88,10 @@ export interface CreateStoryDto {
   priority: WorkItemPriority;
   estimatedHours?: number;
   createdBy: string;  // Required field matching backend API
+  assigneeId?: string;  // Sprint 4 Story 3
+  acceptanceCriteria?: string[];  // Sprint 4 Story 3
+  tags?: string[];  // Sprint 4 Story 3
+  storyPoints?: number;  // Sprint 4 Story 3
 }
 
 export interface UpdateStoryDto {
@@ -92,6 +100,10 @@ export interface UpdateStoryDto {
   priority?: WorkItemPriority;
   estimatedHours?: number;
   actualHours?: number;
+  assigneeId?: string;  // Sprint 4 Story 3
+  acceptanceCriteria?: string[];  // Sprint 4 Story 3
+  tags?: string[];  // Sprint 4 Story 3
+  storyPoints?: number;  // Sprint 4 Story 3
 }
 
 // ==================== Task ====================