diff --git a/src/db/repositories/drizzle/index.ts b/src/db/repositories/drizzle/index.ts
new file mode 100644
index 0000000..d906b48
--- /dev/null
+++ b/src/db/repositories/drizzle/index.ts
@@ -0,0 +1,11 @@
+/**
+ * Drizzle Repository Adapters
+ *
+ * Re-exports all Drizzle implementations of repository interfaces.
+ * These are the ADAPTERS for the repository PORTS.
+ */
+
+export { DrizzleInitiativeRepository } from './initiative.js';
+export { DrizzlePhaseRepository } from './phase.js';
+export { DrizzlePlanRepository } from './plan.js';
+export { DrizzleTaskRepository } from './task.js';
diff --git a/src/db/repositories/drizzle/initiative.ts b/src/db/repositories/drizzle/initiative.ts
new file mode 100644
index 0000000..69ed3e6
--- /dev/null
+++ b/src/db/repositories/drizzle/initiative.ts
@@ -0,0 +1,78 @@
+/**
+ * Drizzle Initiative Repository Adapter
+ *
+ * Implements InitiativeRepository interface using Drizzle ORM.
+ */
+
+import { eq } from 'drizzle-orm';
+import { nanoid } from 'nanoid';
+import type { DrizzleDatabase } from '../../index.js';
+import { initiatives, type Initiative } from '../../schema.js';
+import type {
+  InitiativeRepository,
+  CreateInitiativeData,
+  UpdateInitiativeData,
+} from '../initiative-repository.js';
+
+/**
+ * Drizzle adapter for InitiativeRepository.
+ *
+ * Uses dependency injection for database instance,
+ * enabling isolated test databases.
+ */
+export class DrizzleInitiativeRepository implements InitiativeRepository {
+  constructor(private db: DrizzleDatabase) {}
+
+  async create(data: CreateInitiativeData): Promise<Initiative> {
+    const now = new Date();
+    const initiative = {
+      id: nanoid(),
+      ...data,
+      createdAt: now,
+      updatedAt: now,
+    };
+
+    await this.db.insert(initiatives).values(initiative);
+
+    return initiative as Initiative;
+  }
+
+  async findById(id: string): Promise<Initiative | null> {
+    const result = await this.db
+      .select()
+      .from(initiatives)
+      .where(eq(initiatives.id, id))
+      .limit(1);
+
+    return result[0] ?? null;
+  }
+
+  async findAll(): Promise<Initiative[]> {
+    return this.db.select().from(initiatives);
+  }
+
+  async update(id: string, data: UpdateInitiativeData): Promise<Initiative> {
+    const existing = await this.findById(id);
+    if (!existing) {
+      throw new Error(`Initiative not found: ${id}`);
+    }
+
+    const updated = {
+      ...data,
+      updatedAt: new Date(),
+    };
+
+    await this.db.update(initiatives).set(updated).where(eq(initiatives.id, id));
+
+    return { ...existing, ...updated } as Initiative;
+  }
+
+  async delete(id: string): Promise<void> {
+    const existing = await this.findById(id);
+    if (!existing) {
+      throw new Error(`Initiative not found: ${id}`);
+    }
+
+    await this.db.delete(initiatives).where(eq(initiatives.id, id));
+  }
+}
diff --git a/src/db/repositories/drizzle/phase.ts b/src/db/repositories/drizzle/phase.ts
new file mode 100644
index 0000000..fa17081
--- /dev/null
+++ b/src/db/repositories/drizzle/phase.ts
@@ -0,0 +1,82 @@
+/**
+ * Drizzle Phase Repository Adapter
+ *
+ * Implements PhaseRepository interface using Drizzle ORM.
+ */
+
+import { eq, asc } from 'drizzle-orm';
+import { nanoid } from 'nanoid';
+import type { DrizzleDatabase } from '../../index.js';
+import { phases, type Phase } from '../../schema.js';
+import type {
+  PhaseRepository,
+  CreatePhaseData,
+  UpdatePhaseData,
+} from '../phase-repository.js';
+
+/**
+ * Drizzle adapter for PhaseRepository.
+ *
+ * Uses dependency injection for database instance,
+ * enabling isolated test databases.
+ */
+export class DrizzlePhaseRepository implements PhaseRepository {
+  constructor(private db: DrizzleDatabase) {}
+
+  async create(data: CreatePhaseData): Promise<Phase> {
+    const now = new Date();
+    const phase = {
+      id: nanoid(),
+      ...data,
+      createdAt: now,
+      updatedAt: now,
+    };
+
+    await this.db.insert(phases).values(phase);
+
+    return phase as Phase;
+  }
+
+  async findById(id: string): Promise<Phase | null> {
+    const result = await this.db
+      .select()
+      .from(phases)
+      .where(eq(phases.id, id))
+      .limit(1);
+
+    return result[0] ?? null;
+  }
+
+  async findByInitiativeId(initiativeId: string): Promise<Phase[]> {
+    return this.db
+      .select()
+      .from(phases)
+      .where(eq(phases.initiativeId, initiativeId))
+      .orderBy(asc(phases.number));
+  }
+
+  async update(id: string, data: UpdatePhaseData): Promise<Phase> {
+    const existing = await this.findById(id);
+    if (!existing) {
+      throw new Error(`Phase not found: ${id}`);
+    }
+
+    const updated = {
+      ...data,
+      updatedAt: new Date(),
+    };
+
+    await this.db.update(phases).set(updated).where(eq(phases.id, id));
+
+    return { ...existing, ...updated } as Phase;
+  }
+
+  async delete(id: string): Promise<void> {
+    const existing = await this.findById(id);
+    if (!existing) {
+      throw new Error(`Phase not found: ${id}`);
+    }
+
+    await this.db.delete(phases).where(eq(phases.id, id));
+  }
+}
diff --git a/src/db/repositories/drizzle/plan.ts b/src/db/repositories/drizzle/plan.ts
new file mode 100644
index 0000000..f116a8c
--- /dev/null
+++ b/src/db/repositories/drizzle/plan.ts
@@ -0,0 +1,82 @@
+/**
+ * Drizzle Plan Repository Adapter
+ *
+ * Implements PlanRepository interface using Drizzle ORM.
+ */
+
+import { eq, asc } from 'drizzle-orm';
+import { nanoid } from 'nanoid';
+import type { DrizzleDatabase } from '../../index.js';
+import { plans, type Plan } from '../../schema.js';
+import type {
+  PlanRepository,
+  CreatePlanData,
+  UpdatePlanData,
+} from '../plan-repository.js';
+
+/**
+ * Drizzle adapter for PlanRepository.
+ *
+ * Uses dependency injection for database instance,
+ * enabling isolated test databases.
+ */
+export class DrizzlePlanRepository implements PlanRepository {
+  constructor(private db: DrizzleDatabase) {}
+
+  async create(data: CreatePlanData): Promise<Plan> {
+    const now = new Date();
+    const plan = {
+      id: nanoid(),
+      ...data,
+      createdAt: now,
+      updatedAt: now,
+    };
+
+    await this.db.insert(plans).values(plan);
+
+    return plan as Plan;
+  }
+
+  async findById(id: string): Promise<Plan | null> {
+    const result = await this.db
+      .select()
+      .from(plans)
+      .where(eq(plans.id, id))
+      .limit(1);
+
+    return result[0] ?? null;
+  }
+
+  async findByPhaseId(phaseId: string): Promise<Plan[]> {
+    return this.db
+      .select()
+      .from(plans)
+      .where(eq(plans.phaseId, phaseId))
+      .orderBy(asc(plans.number));
+  }
+
+  async update(id: string, data: UpdatePlanData): Promise<Plan> {
+    const existing = await this.findById(id);
+    if (!existing) {
+      throw new Error(`Plan not found: ${id}`);
+    }
+
+    const updated = {
+      ...data,
+      updatedAt: new Date(),
+    };
+
+    await this.db.update(plans).set(updated).where(eq(plans.id, id));
+
+    return { ...existing, ...updated } as Plan;
+  }
+
+  async delete(id: string): Promise<void> {
+    const existing = await this.findById(id);
+    if (!existing) {
+      throw new Error(`Plan not found: ${id}`);
+    }
+
+    await this.db.delete(plans).where(eq(plans.id, id));
+  }
+}
diff --git a/src/db/repositories/drizzle/task.ts b/src/db/repositories/drizzle/task.ts
new file mode 100644
index 0000000..2d4ad22
--- /dev/null
+++ b/src/db/repositories/drizzle/task.ts
@@ -0,0 +1,82 @@
+/**
+ * Drizzle Task Repository Adapter
+ *
+ * Implements TaskRepository interface using Drizzle ORM.
+ */
+
+import { eq, asc } from 'drizzle-orm';
+import { nanoid } from 'nanoid';
+import type { DrizzleDatabase } from '../../index.js';
+import { tasks, type Task } from '../../schema.js';
+import type {
+  TaskRepository,
+  CreateTaskData,
+  UpdateTaskData,
+} from '../task-repository.js';
+
+/**
+ * Drizzle adapter for TaskRepository.
+ *
+ * Uses dependency injection for database instance,
+ * enabling isolated test databases.
+ */
+export class DrizzleTaskRepository implements TaskRepository {
+  constructor(private db: DrizzleDatabase) {}
+
+  async create(data: CreateTaskData): Promise<Task> {
+    const now = new Date();
+    const task = {
+      id: nanoid(),
+      ...data,
+      createdAt: now,
+      updatedAt: now,
+    };
+
+    await this.db.insert(tasks).values(task);
+
+    return task as Task;
+  }
+
+  async findById(id: string): Promise<Task | null> {
+    const result = await this.db
+      .select()
+      .from(tasks)
+      .where(eq(tasks.id, id))
+      .limit(1);
+
+    return result[0] ?? null;
+  }
+
+  async findByPlanId(planId: string): Promise<Task[]> {
+    return this.db
+      .select()
+      .from(tasks)
+      .where(eq(tasks.planId, planId))
+      .orderBy(asc(tasks.order));
+  }
+
+  async update(id: string, data: UpdateTaskData): Promise<Task> {
+    const existing = await this.findById(id);
+    if (!existing) {
+      throw new Error(`Task not found: ${id}`);
+    }
+
+    const updated = {
+      ...data,
+      updatedAt: new Date(),
+    };
+
+    await this.db.update(tasks).set(updated).where(eq(tasks.id, id));
+
+    return { ...existing, ...updated } as Task;
+  }
+
+  async delete(id: string): Promise<void> {
+    const existing = await this.findById(id);
+    if (!existing) {
+      throw new Error(`Task not found: ${id}`);
+    }
+
+    await this.db.delete(tasks).where(eq(tasks.id, id));
+  }
+}