Aspects are presented herein of apparatuses, systems, and methods for secondary cell group (SCG) addition. A wireless device may establish communication with a first base station that is comprised a master cell group (MCG). The wireless device may receive signaling from the first base station configuring a second base station in a secondary cell group (SCG). The wireless device may establish communication with the second base station based on the signaling received from the first base station. At a first time, the wireless device may set the second base station in a deactivated state based on the signaling from the first base station configuring the second base station or establishing communication with the second base station. At a later time, the wireless device may set the second base station in an activated state and communicate with the first base station and the second base station.