diff --git a/integration-tests/api/__tests__/admin/__snapshots__/customer.js.snap b/integration-tests/api/__tests__/admin/__snapshots__/customer.js.snap
index 2c77349148..a8a7e640f5 100644
--- a/integration-tests/api/__tests__/admin/__snapshots__/customer.js.snap
+++ b/integration-tests/api/__tests__/admin/__snapshots__/customer.js.snap
@@ -62,6 +62,7 @@ Object {
   "deleted_at": null,
   "email": "test1@email.com",
   "first_name": null,
+  "groups": Array [],
   "has_account": false,
   "id": "test-customer-1",
   "last_name": null,
diff --git a/integration-tests/api/__tests__/admin/customer.js b/integration-tests/api/__tests__/admin/customer.js
index 283d716894..3fd0417991 100644
--- a/integration-tests/api/__tests__/admin/customer.js
+++ b/integration-tests/api/__tests__/admin/customer.js
@@ -56,7 +56,7 @@ describe("/admin/customers", () => {
         })
 
       expect(response.status).toEqual(200)
-      expect(response.data.count).toEqual(4)
+      expect(response.data.count).toEqual(5)
       expect(response.data.customers).toEqual(
         expect.arrayContaining([
           expect.objectContaining({
@@ -228,6 +228,106 @@ describe("/admin/customers", () => {
         })
       )
     })
+
+    it("Correctly updates customer groups", async () => {
+      const api = useApi()
+      let response = await api
+        .post(
+          "/admin/customers/test-customer-3?expand=groups",
+          {
+            groups: [{ id: "test-group-4" }],
+          },
+          {
+            headers: {
+              Authorization: "Bearer test_token",
+            },
+          }
+        )
+        .catch((err) => {
+          console.log(err)
+        })
+
+      expect(response.status).toEqual(200)
+      expect(response.data.customer.groups).toEqual(
+        expect.arrayContaining([
+          expect.objectContaining({ id: "test-group-4", name: "test-group-4" }),
+        ])
+      )
+
+      // Try adding a non existing group
+
+      response = await api
+        .post(
+          "/admin/customers/test-customer-3?expand=groups",
+          {
+            groups: [{ id: "test-group-4" }, { id: "fake-group-0" }],
+          },
+          {
+            headers: {
+              Authorization: "Bearer test_token",
+            },
+          }
+        )
+        .catch((err) => {
+          console.log(err)
+        })
+
+      expect(response.status).toEqual(200)
+      expect(response.data.customer.groups.length).toEqual(1)
+      expect(response.data.customer.groups).toEqual(
+        expect.arrayContaining([
+          expect.objectContaining({ id: "test-group-4", name: "test-group-4" }),
+        ])
+      )
+
+      // Delete all groups
+
+      response = await api
+        .post(
+          "/admin/customers/test-customer-3?expand=groups",
+          {
+            groups: [],
+          },
+          {
+            headers: {
+              Authorization: "Bearer test_token",
+            },
+          }
+        )
+        .catch((err) => {
+          console.log(err)
+        })
+
+      expect(response.status).toEqual(200)
+      expect(response.data.customer.groups.length).toEqual(0)
+
+      // Adding a group to a customer with already existing groups.
+
+      response = await api
+        .post(
+          "/admin/customers/test-customer-5?expand=groups",
+          {
+            groups: [{ id: "test-group-5" }, { id: "test-group-4" }],
+          },
+          {
+            headers: {
+              Authorization: "Bearer test_token",
+            },
+          }
+        )
+        .catch((err) => {
+          console.log(err)
+        })
+
+      expect(response.status).toEqual(200)
+      expect(response.data.customer.groups.length).toEqual(2)
+      expect(response.data.customer.groups).toEqual(
+        expect.arrayContaining([
+          expect.objectContaining({ id: "test-group-4", name: "test-group-4" }),
+          expect.objectContaining({ id: "test-group-5", name: "test-group-5" }),
+        ])
+      )
+    })
   })
 
   describe("GET /admin/customers/:id", () => {
@@ -278,7 +378,7 @@ describe("/admin/customers", () => {
       const api = useApi()
 
       const response = await api
-        .get("/admin/customers/test-customer-1?expand=billing_address", {
+        .get("/admin/customers/test-customer-1?expand=billing_address,groups", {
           headers: {
             Authorization: "Bearer test_token",
           },
@@ -295,6 +395,7 @@ describe("/admin/customers", () => {
           created_at: expect.any(String),
           updated_at: expect.any(String),
         },
+        groups: [],
         created_at: expect.any(String),
         updated_at: expect.any(String),
       })
diff --git a/integration-tests/api/helpers/customer-seeder.js b/integration-tests/api/helpers/customer-seeder.js
index c0db241b4e..f0d795ea39 100644
--- a/integration-tests/api/helpers/customer-seeder.js
+++ b/integration-tests/api/helpers/customer-seeder.js
@@ -36,8 +36,24 @@ module.exports = async (connection, data = {}) => {
     has_account: true,
   })
 
+  await manager.insert(Customer, {
+    id: "test-customer-5",
+    email: "test5@email.com",
+    groups: [{ id: "test-group-5", name: "test-group-5" }],
+  })
+
   await manager.insert(CustomerGroup, {
     id: "customer-group-1",
     name: "vip-customers",
   })
+
+  await manager.insert(CustomerGroup, {
+    id: "test-group-4",
+    name: "test-group-4",
+  })
+
+  await manager.insert(CustomerGroup, {
+    id: "test-group-5",
+    name: "test-group-5",
+  })
 }
diff --git a/packages/medusa/src/api/routes/admin/customers/update-customer.ts b/packages/medusa/src/api/routes/admin/customers/update-customer.ts
index 11c0a8b419..32607ff6cc 100644
--- a/packages/medusa/src/api/routes/admin/customers/update-customer.ts
+++ b/packages/medusa/src/api/routes/admin/customers/update-customer.ts
@@ -1,7 +1,17 @@
-import { IsEmail, IsObject, IsOptional, IsString } from "class-validator"
+import {
+  IsArray,
+  IsEmail,
+  IsObject,
+  IsOptional,
+  IsString,
+  ValidateNested,
+} from "class-validator"
 import { MedusaError } from "medusa-core-utils"
 import CustomerService from "../../../../services/customer"
 import { validator } from "../../../../utils/validator"
+import { defaultAdminCustomersRelations } from "."
+import { Type } from "class-transformer"
+import { FindParams } from "../../../../types/common"
 
 /**
  * @oas [post] /customers/{id}
@@ -31,6 +41,16 @@ import { validator } from "../../../../utils/validator"
  *           password:
  *             type: string
  *             description: The Customer's password.
+ *           groups:
+ *             type: array
+ *             description: A list of customer groups to which the customer belongs.
+ *             items:
+ *               required:
+ *                 - id
+ *               properties:
+ *                 id:
+ *                   description: The id of a customer group
+ *                   type: string
  *           metadata:
  *             type: object
  *             description: Metadata for the customer.
@@ -49,27 +69,43 @@ import { validator } from "../../../../utils/validator"
 export default async (req, res) => {
   const { id } = req.params
 
-  const validated = await validator(AdminPostCustomersCustomerReq, req.body)
+  const validatedBody = await validator(AdminPostCustomersCustomerReq, req.body)
+  const validatedQuery = await validator(FindParams, req.query)
 
   const customerService: CustomerService = req.scope.resolve("customerService")
 
   let customer = await customerService.retrieve(id)
 
-  if (validated.email && customer.has_account) {
+  if (validatedBody.email && customer.has_account) {
     throw new MedusaError(
       MedusaError.Types.INVALID_DATA,
       "Email cannot be changed when the user has registered their account"
     )
   }
 
-  await customerService.update(id, validated)
+  await customerService.update(id, validatedBody)
+
+  let expandFields: string[] = []
+  if (validatedQuery.expand) {
+    expandFields = validatedQuery.expand.split(",")
+  }
+
+  const findConfig = {
+    relations: expandFields.length
+      ? expandFields
+      : defaultAdminCustomersRelations,
+  }
+
+  customer = await customerService.retrieve(id, findConfig)
 
-  customer = await customerService.retrieve(id, {
-    relations: ["orders"],
-  })
   res.status(200).json({ customer })
 }
 
+class Group {
+  @IsString()
+  id: string
+}
+
 export class AdminPostCustomersCustomerReq {
   @IsEmail()
   @IsOptional()
@@ -94,4 +130,10 @@ export class AdminPostCustomersCustomerReq {
   @IsObject()
   @IsOptional()
   metadata?: object
+
+  @IsArray()
+  @IsOptional()
+  @Type(() => Group)
+  @ValidateNested({ each: true })
+  groups?: Group[]
 }
diff --git a/packages/medusa/src/models/customer.ts b/packages/medusa/src/models/customer.ts
index f3c27f9f27..7e67a86c32 100644
--- a/packages/medusa/src/models/customer.ts
+++ b/packages/medusa/src/models/customer.ts
@@ -43,7 +43,10 @@ export class Customer {
   @JoinColumn({ name: "billing_address_id" })
   billing_address: Address
 
-  @OneToMany(() => Address, (address) => address.customer)
+  @OneToMany(
+    () => Address,
+    (address) => address.customer
+  )
   shipping_addresses: Address[]
 
   @Column({ nullable: true, select: false })
@@ -55,9 +58,23 @@ export class Customer {
   @Column({ default: false })
   has_account: boolean
 
-  @OneToMany(() => Order, (order) => order.customer)
+  @OneToMany(
+    () => Order,
+    (order) => order.customer
+  )
   orders: Order[]
 
+  @JoinTable({
+    name: "customer_group_customers",
+    inverseJoinColumn: {
+      name: "customer_group_id",
+      referencedColumnName: "id",
+    },
+    joinColumn: {
+      name: "customer_id",
+      referencedColumnName: "id",
+    },
+  })
   @ManyToMany(() => CustomerGroup, { cascade: true })
   groups: CustomerGroup[]
 
diff --git a/packages/medusa/src/services/__tests__/customer.js b/packages/medusa/src/services/__tests__/customer.js
index 0c3ed6dd50..319e954c17 100644
--- a/packages/medusa/src/services/__tests__/customer.js
+++ b/packages/medusa/src/services/__tests__/customer.js
@@ -8,6 +8,13 @@ const eventBusService = {
   },
 }
 
+const customerGroupService = {
+  withTransaction: function() {
+    return this
+  },
+  list: jest.fn().mockImplementation(() => Promise.resolve()),
+}
+
 describe("CustomerService", () => {
   describe("retrieve", () => {
     const customerRepository = MockRepository({
@@ -86,7 +93,7 @@ describe("CustomerService", () => {
 
   describe("create", () => {
     const customerRepository = MockRepository({
-      findOne: query => {
+      findOne: (query) => {
         if (query.where.email === "tony@stark.com") {
           return Promise.resolve({
             id: IdMap.getId("exists"),
@@ -162,14 +169,14 @@ describe("CustomerService", () => {
 
   describe("update", () => {
     const customerRepository = MockRepository({
-      findOne: query => {
+      findOne: (query) => {
         return Promise.resolve({ id: IdMap.getId("ironman") })
       },
     })
 
     const addressRepository = MockRepository({
-      create: data => data,
-      save: data => Promise.resolve(data),
+      create: (data) => data,
+      save: (data) => Promise.resolve(data),
     })
 
     const customerService = new CustomerService({
@@ -246,9 +253,50 @@ describe("CustomerService", () => {
     })
   })
 
+  describe("update customer groups", () => {
+    const customerRepository = MockRepository({
+      findOne: (query) => {
+        return Promise.resolve({ id: IdMap.getId("ironman") })
+      },
+    })
+
+    const addressRepository = MockRepository({
+      create: (data) => data,
+      save: (data) => Promise.resolve(data),
+    })
+
+    const customerGroupRepository = MockRepository({
+      findByIds: jest.fn().mockImplementation(() => Promise.resolve()),
+    })
+
+    const customerService = new CustomerService({
+      manager: MockManager,
+      addressRepository,
+      customerRepository,
+      customerGroupRepository,
+      customerGroupService,
+      eventBusService,
+    })
+
+    beforeEach(async () => {
+      jest.clearAllMocks()
+    })
+
+    it("calls `customerGroupService.list` if `groups` prop is received as a param", async () => {
+      await customerService.update(IdMap.getId("ironman"), {
+        groups: [{ id: "group-id" }],
+      })
+
+      expect(customerGroupService.list).toBeCalledTimes(1)
+      expect(customerGroupService.list).toBeCalledWith({ id: ["group-id"] })
+
+      expect(customerRepository.save).toBeCalledTimes(1)
+    })
+  })
+
   describe("updateAddress", () => {
     const addressRepository = MockRepository({
-      findOne: query => {
+      findOne: (query) => {
         return Promise.resolve({
           id: IdMap.getId("hollywood-boulevard"),
           address_1: "Hollywood Boulevard 2",
@@ -312,7 +360,7 @@ describe("CustomerService", () => {
 
   describe("removeAddress", () => {
     const addressRepository = MockRepository({
-      findOne: query => {
+      findOne: (query) => {
         return Promise.resolve({
           id: IdMap.getId("hollywood-boulevard"),
           address_1: "Hollywood Boulevard 2",
@@ -345,7 +393,7 @@ describe("CustomerService", () => {
 
   describe("delete", () => {
     const customerRepository = MockRepository({
-      findOne: query => {
+      findOne: (query) => {
         return Promise.resolve({ id: IdMap.getId("ironman") })
       },
     })
diff --git a/packages/medusa/src/services/customer-group.ts b/packages/medusa/src/services/customer-group.ts
index 80cc6b9b82..cb1d98fa8f 100644
--- a/packages/medusa/src/services/customer-group.ts
+++ b/packages/medusa/src/services/customer-group.ts
@@ -3,6 +3,8 @@ import { BaseService } from "medusa-interfaces"
 import { DeepPartial, EntityManager } from "typeorm"
 import { CustomerGroup } from ".."
 import { CustomerGroupRepository } from "../repositories/customer-group"
+import { FindConfig } from "../types/common"
+import { FilterableCustomerGroupProps } from "../types/customer-groups"
 
 type CustomerGroupConstructorProps = {
   manager: EntityManager
@@ -64,6 +66,25 @@ class CustomerGroupService extends BaseService {
       }
     })
   }
+
+  /**
+   * List customer groups.
+   *
+   * @param {Object} selector - the query object for find
+   * @param {Object} config - the config to be used for find
+   * @return {Promise} the result of the find operation
+   */
+  async list(
+    selector: FilterableCustomerGroupProps = {},
+    config: FindConfig<CustomerGroup>
+  ): Promise<CustomerGroup[]> {
+    const cgRepo: CustomerGroupRepository = this.manager_.getCustomRepository(
+      this.customerGroupRepository_
+    )
+
+    const query = this.buildQuery_(selector, config)
+    return await cgRepo.find(query)
+  }
 }
 
 export default CustomerGroupService
diff --git a/packages/medusa/src/services/customer.js b/packages/medusa/src/services/customer.js
index 40aee34bc1..97569c21bb 100644
--- a/packages/medusa/src/services/customer.js
+++ b/packages/medusa/src/services/customer.js
@@ -21,6 +21,7 @@ class CustomerService extends BaseService {
     customerRepository,
     eventBusService,
     addressRepository,
+    customerGroupService,
   }) {
     super()
 
@@ -35,6 +36,8 @@ class CustomerService extends BaseService {
 
     /** @private @const {AddressRepository} */
     this.addressRepository_ = addressRepository
+
+    this.customerGroupService_ = customerGroupService
   }
 
   withTransaction(transactionManager) {
@@ -60,7 +63,9 @@ class CustomerService extends BaseService {
    * @return {string} the validated email
    */
   validateEmail_(email) {
-    const schema = Validator.string().email().required()
+    const schema = Validator.string()
+      .email()
+      .required()
     const { value, error } = schema.validate(email)
     if (error) {
       throw new MedusaError(
@@ -391,6 +396,7 @@ class CustomerService extends BaseService {
         metadata,
         billing_address,
         billing_address_id,
+        groups,
         ...rest
       } = update
 
@@ -417,6 +423,11 @@ class CustomerService extends BaseService {
         customer.password_hash = await this.hashPassword_(password)
       }
 
+      if (groups) {
+        const id = groups.map((g) => g.id)
+        customer.groups = await this.customerGroupService_.list({ id })
+      }
+
       const updated = await customerRepository.save(customer)
 
       await this.eventBus_
diff --git a/packages/medusa/src/types/customer-groups.ts b/packages/medusa/src/types/customer-groups.ts
new file mode 100644
index 0000000000..f2829205c9
--- /dev/null
+++ b/packages/medusa/src/types/customer-groups.ts
@@ -0,0 +1,10 @@
+import { ValidateNested } from "class-validator"
+import { IsType } from "../utils/validators/is-type"
+
+import { StringComparisonOperator } from "./common"
+
+export class FilterableCustomerGroupProps {
+  @ValidateNested()
+  @IsType([String, [String], StringComparisonOperator])
+  id?: string | string[] | StringComparisonOperator
+}