diff --git a/apps/backend/src/app.module.ts b/apps/backend/src/app.module.ts
index bd206d3..334aae4 100644
--- a/apps/backend/src/app.module.ts
+++ b/apps/backend/src/app.module.ts
@@ -4,9 +4,10 @@ import { PrismaModule } from 'nestjs-prisma';
 import { AppController } from './app.controller';
 import { AppService } from './app.service';
 import { EventModule } from './event/event.module';
+import { GroupsModule } from './groups/groups.module';
 
 @Module({
-  imports: [PrismaModule.forRoot({ isGlobal: true }), EventModule],
+  imports: [PrismaModule.forRoot({ isGlobal: true }), EventModule, GroupsModule],
   controllers: [AppController],
   providers: [AppService],
 })
diff --git a/apps/backend/src/groups/groups.controller.ts b/apps/backend/src/groups/groups.controller.ts
new file mode 100644
index 0000000..6af1128
--- /dev/null
+++ b/apps/backend/src/groups/groups.controller.ts
@@ -0,0 +1,54 @@
+import { Body, Controller, Delete, Get, Param, Patch, Post } from '@nestjs/common';
+import { Prisma, Role } from '@prisma/client';
+
+import { GroupsService } from './groups.service';
+
+@Controller('groups')
+export class GroupsController {
+  constructor(private readonly groupsService: GroupsService) {}
+
+  @Post()
+  create(@Body() data: Prisma.GroupCreateInput) {
+    return this.groupsService.create(data);
+  }
+
+  @Get()
+  findAll() {
+    return this.groupsService.findAll();
+  }
+
+  @Get(':id')
+  findOne(@Param('id') id: string) {
+    return this.groupsService.findOne(Number(id));
+  }
+
+  @Get(':id/members')
+  findMembers(@Param('id') id: string) {
+    return this.groupsService.findMembers(Number(id));
+  }
+
+  @Patch(':id')
+  update(@Param('id') id: string, @Body() data: Prisma.GroupUpdateInput) {
+    return this.groupsService.update(Number(id), data);
+  }
+
+  @Delete(':id')
+  remove(@Param('id') id: string) {
+    return this.groupsService.remove(Number(id));
+  }
+
+  @Post(':id/members/:userId')
+  addMember(@Param('id') id: string, @Param('userId') userId: string) {
+    return this.groupsService.addMember(Number(id), Number(userId));
+  }
+
+  @Patch(':id/members/:userId')
+  updateRole(@Param('id') id: string, @Param('userId') userId: string, @Body() newRole: { role: Role }) {
+    return this.groupsService.updateMemberRole(Number(id), Number(userId), newRole);
+  }
+
+  @Delete(':id/members/:userId')
+  removeMember(@Param('id') id: string, @Param('userId') userId: string) {
+    return this.groupsService.removeMember(Number(id), Number(userId));
+  }
+}
diff --git a/apps/backend/src/groups/groups.module.ts b/apps/backend/src/groups/groups.module.ts
new file mode 100644
index 0000000..befe35b
--- /dev/null
+++ b/apps/backend/src/groups/groups.module.ts
@@ -0,0 +1,10 @@
+import { Module } from '@nestjs/common';
+
+import { GroupsController } from './groups.controller';
+import { GroupsService } from './groups.service';
+
+@Module({
+  controllers: [GroupsController],
+  providers: [GroupsService],
+})
+export class GroupsModule {}
diff --git a/apps/backend/src/groups/groups.service.ts b/apps/backend/src/groups/groups.service.ts
new file mode 100644
index 0000000..61aab95
--- /dev/null
+++ b/apps/backend/src/groups/groups.service.ts
@@ -0,0 +1,120 @@
+import { Injectable, NotFoundException } from '@nestjs/common';
+import { Group, GroupMembers, Prisma, Role, User } from '@prisma/client';
+import { PrismaService } from 'nestjs-prisma';
+
+@Injectable()
+export class GroupsService {
+  constructor(private readonly prisma: PrismaService) {}
+
+  async create(data: Prisma.GroupCreateInput): Promise<Group> {
+    try {
+      return await this.prisma.group.create({ data });
+    } catch {
+      throw new NotFoundException('Group could not be created');
+    }
+  }
+
+  async findAll(): Promise<Group[]> {
+    try {
+      return await this.prisma.group.findMany();
+    } catch {
+      throw new NotFoundException('Groups could not be found');
+    }
+  }
+
+  async findOne(id: number): Promise<Group> {
+    try {
+      return await this.prisma.group.findUnique({ where: { id } });
+    } catch {
+      throw new NotFoundException(`Group with ID ${id} not found`);
+    }
+  }
+
+  async findMembers(id: number): Promise<{ user: User; role: Role }[]> {
+    const groupMembers = await this.prisma.groupMembers.findMany({
+      where: { groupId: id },
+      include: { User: true },
+    });
+    if (!groupMembers) {
+      throw new NotFoundException(`Group with ID ${id} not found`);
+    }
+    return groupMembers.map((groupMember) => ({
+      user: groupMember.User,
+      role: groupMember.role,
+    }));
+  }
+
+  async update(id: number, data: Prisma.GroupUpdateInput): Promise<Group> {
+    try {
+      return await this.prisma.group.update({ where: { id }, data });
+    } catch {
+      throw new NotFoundException(`Group with ID ${id} could not be updated`);
+    }
+  }
+
+  async remove(id: number): Promise<Group> {
+    try {
+      return await this.prisma.group.delete({ where: { id } });
+    } catch {
+      throw new NotFoundException(`Group with ID ${id} could not be deleted`);
+    }
+  }
+
+  async addMember(groupId: number, userId: number): Promise<GroupMembers> {
+    if (await this.prisma.groupMembers.findUnique({ where: { groupId_userId: { groupId, userId } } })) {
+      throw new NotFoundException('User is already a member of the group');
+    }
+    if (!(await this.prisma.user.findUnique({ where: { id: userId } }))) {
+      throw new NotFoundException('User does not exist');
+    }
+    try {
+      return await this.prisma.groupMembers.create({
+        data: {
+          groupId,
+          userId,
+        },
+      });
+    } catch {
+      throw new NotFoundException('User could not be added to the group');
+    }
+  }
+
+  async updateMemberRole(groupId: number, userId: number, newRole: { role: Role }): Promise<GroupMembers> {
+    if (!(await this.prisma.groupMembers.findUnique({ where: { groupId_userId: { groupId, userId } } }))) {
+      throw new NotFoundException(`User with id: ${userId} is not a member of the group.`);
+    }
+    try {
+      return await this.prisma.groupMembers.update({
+        where: {
+          groupId_userId: {
+            groupId,
+            userId,
+          },
+        },
+        data: {
+          role: newRole.role,
+        },
+      });
+    } catch {
+      throw new NotFoundException('User role could not be updated.');
+    }
+  }
+
+  async removeMember(groupId: number, userId: number): Promise<GroupMembers> {
+    if (!(await this.prisma.groupMembers.findUnique({ where: { groupId_userId: { groupId, userId } } }))) {
+      throw new NotFoundException('User is not a member of the group');
+    }
+    try {
+      return await this.prisma.groupMembers.delete({
+        where: {
+          groupId_userId: {
+            groupId,
+            userId,
+          },
+        },
+      });
+    } catch {
+      throw new NotFoundException('User could not be removed from the group');
+    }
+  }
+}