diff --git a/front/admin/db.ts b/front/admin/db.ts
index 97534959b7520..ee920bdee0aab 100644
--- a/front/admin/db.ts
+++ b/front/admin/db.ts
@@ -65,6 +65,7 @@ import {
 } from "@app/lib/models/workspace";
 import { ContentFragmentModel } from "@app/lib/resources/storage/models/content_fragment";
 import { FileModel } from "@app/lib/resources/storage/models/files";
+import { GroupMembershipModel } from "@app/lib/resources/storage/models/group_memberships";
 import { GroupModel } from "@app/lib/resources/storage/models/groups";
 import { KeyModel } from "@app/lib/resources/storage/models/keys";
 // Labs - Can be removed at all times if a solution is dropped
@@ -92,6 +93,7 @@ async function main() {
   await MembershipModel.sync({ alter: true });
   await MembershipInvitation.sync({ alter: true });
   await GroupModel.sync({ alter: true });
+  await GroupMembershipModel.sync({ alter: true });
 
   await App.sync({ alter: true });
   await Dataset.sync({ alter: true });
diff --git a/front/lib/resources/group_resource.ts b/front/lib/resources/group_resource.ts
index bbfd9b3deee0c..a858247bb6678 100644
--- a/front/lib/resources/group_resource.ts
+++ b/front/lib/resources/group_resource.ts
@@ -9,9 +9,13 @@ import type {
 
 import type { Authenticator } from "@app/lib/auth";
 import { BaseResource } from "@app/lib/resources/base_resource";
+import { MembershipResource } from "@app/lib/resources/membership_resource";
+import { GroupMembershipModel } from "@app/lib/resources/storage/models/group_memberships";
 import { GroupModel } from "@app/lib/resources/storage/models/groups";
 import type { ReadonlyAttributesType } from "@app/lib/resources/storage/types";
 import { getResourceIdFromSId, makeSId } from "@app/lib/resources/string_ids";
+import { UserResource } from "@app/lib/resources/user_resource";
+import { renderLightWorkspaceType } from "@app/lib/workspace";
 
 // Attributes are marked as read-only to reflect the stateless nature of our Resource.
 // This design will be moved up to BaseResource once we transition away from Sequelize.
@@ -177,6 +181,51 @@ export class GroupResource extends BaseResource<GroupModel> {
     return new this(GroupModel, group.get());
   }
 
+  static async addMember(
+    auth: Authenticator,
+    groupId: string,
+    userId: string,
+    transaction?: Transaction
+  ): Promise<void> {
+    const owner = auth.getNonNullableWorkspace();
+    const [group, user] = await Promise.all([
+      this.fetchById(auth, groupId),
+      UserResource.fetchById(userId),
+    ]);
+
+    if (!group) {
+      throw new Error("Group not found.");
+    }
+    if (group.type !== "regular") {
+      throw new Error("Cannot add members to non-regular groups.");
+    }
+    if (!user) {
+      throw new Error("User not found.");
+    }
+
+    const workspace = renderLightWorkspaceType({ workspace: owner });
+    const membership =
+      await MembershipResource.getActiveMembershipOfUserInWorkspace({
+        user,
+        workspace,
+        transaction,
+      });
+
+    if (!membership) {
+      throw new Error("User is not a member of the workspace.");
+    }
+
+    await GroupMembershipModel.create(
+      {
+        groupId: group.id,
+        userId: user.id,
+        workspaceId: owner.id,
+        startAt: new Date(),
+      },
+      { transaction }
+    );
+  }
+
   toJSON() {
     return {
       id: this.id,
diff --git a/front/lib/resources/storage/models/group_memberships.ts b/front/lib/resources/storage/models/group_memberships.ts
new file mode 100644
index 0000000000000..be6a817edac62
--- /dev/null
+++ b/front/lib/resources/storage/models/group_memberships.ts
@@ -0,0 +1,112 @@
+import type {
+  CreationOptional,
+  ForeignKey,
+  InferAttributes,
+  InferCreationAttributes,
+} from "sequelize";
+import { DataTypes, Model, Op } from "sequelize";
+
+import { User } from "@app/lib/models/user";
+import { Workspace } from "@app/lib/models/workspace";
+import { frontSequelize } from "@app/lib/resources/storage";
+import { GroupModel } from "@app/lib/resources/storage/models/groups";
+
+export class GroupMembershipModel extends Model<
+  InferAttributes<GroupMembershipModel>,
+  InferCreationAttributes<GroupMembershipModel>
+> {
+  declare id: CreationOptional<number>;
+  declare createdAt: CreationOptional<Date>;
+  declare updatedAt: CreationOptional<Date>;
+
+  declare startAt: Date;
+  declare endAt: Date | null;
+
+  declare groupId: ForeignKey<GroupModel["id"]>;
+  declare userId: ForeignKey<User["id"]>;
+  declare workspaceId: ForeignKey<Workspace["id"]>;
+
+  static async checkOverlap(
+    userId: number,
+    groupId: number,
+    startAt: Date,
+    endAt: Date | null,
+    excludeId?: number
+  ) {
+    const where: any = {
+      userId,
+      groupId,
+      [Op.or]: [{ endAt: null }, { endAt: { [Op.gt]: startAt } }],
+      startAt: { [Op.lt]: endAt || new Date(8640000000000000) }, // Max date if endAt is null
+    };
+
+    if (excludeId) {
+      where.id = { [Op.ne]: excludeId };
+    }
+
+    const overlapping = await this.findOne({ where });
+    return !!overlapping;
+  }
+}
+GroupMembershipModel.init(
+  {
+    id: {
+      type: DataTypes.INTEGER,
+      autoIncrement: true,
+      primaryKey: true,
+    },
+    createdAt: {
+      type: DataTypes.DATE,
+      allowNull: false,
+      defaultValue: DataTypes.NOW,
+    },
+    updatedAt: {
+      type: DataTypes.DATE,
+      allowNull: false,
+      defaultValue: DataTypes.NOW,
+    },
+    startAt: {
+      type: DataTypes.DATE,
+      allowNull: false,
+    },
+    endAt: {
+      type: DataTypes.DATE,
+      allowNull: true,
+    },
+  },
+  {
+    modelName: "group_memberships",
+    sequelize: frontSequelize,
+    indexes: [{ fields: ["userId", "groupId"] }],
+    validate: {
+      async noOverlap() {
+        if (
+          await GroupMembershipModel.checkOverlap(
+            this.userId as number,
+            this.groupId as number,
+            this.startAt as Date,
+            this.endAt as Date | null,
+            this.id as number
+          )
+        ) {
+          throw new Error("Overlapping group membership period");
+        }
+      },
+    },
+  }
+);
+User.hasMany(GroupMembershipModel, {
+  foreignKey: { allowNull: false },
+  onDelete: "CASCADE",
+});
+GroupModel.hasMany(GroupMembershipModel, {
+  foreignKey: { allowNull: false },
+  onDelete: "CASCADE",
+});
+Workspace.hasMany(GroupMembershipModel, {
+  foreignKey: { allowNull: false },
+  onDelete: "CASCADE",
+});
+GroupMembershipModel.belongsTo(User);
+GroupMembershipModel.belongsTo(GroupModel);
+GroupMembershipModel.belongsTo(Workspace);
diff --git a/front/migrations/db/migration_47.sql b/front/migrations/db/migration_47.sql
new file mode 100644
index 0000000000000..f2235847c8683
--- /dev/null
+++ b/front/migrations/db/migration_47.sql
@@ -0,0 +1,13 @@
+-- Migration created on Jul 25, 2024
+CREATE TABLE IF NOT EXISTS "group_memberships" (
+    "id"  SERIAL , 
+    "createdAt" TIMESTAMP WITH TIME ZONE NOT NULL, 
+    "updatedAt" TIMESTAMP WITH TIME ZONE NOT NULL, 
+    "startAt" TIMESTAMP WITH TIME ZONE NOT NULL,
+    "endAt" TIMESTAMP WITH TIME ZONE, 
+    "userId" INTEGER NOT NULL REFERENCES "users" ("id") ON DELETE CASCADE ON UPDATE CASCADE, 
+    "groupId" INTEGER NOT NULL REFERENCES "groups" ("id") ON DELETE CASCADE ON UPDATE CASCADE, 
+    "workspaceId" INTEGER NOT NULL REFERENCES "workspaces" ("id") ON DELETE CASCADE ON UPDATE CASCADE, 
+    PRIMARY KEY ("id")
+);
+CREATE INDEX "group_memberships_user_id_group_id" ON "group_memberships" ("userId", "groupId");