A device for a hydraulic actuating system, e.g., a motor vehicle brake, a clutch or a gear selector, may include the following components arranged in one housing, forming a main module: at least one pressure supply device driven by an electric motor drive, and a valve arrangement comprising at least one solenoid valve. The device may further include an electrical control unit (ECU) and valve output stages and sensors. The main module may be electrically and/or hydraulically connected to at least one further system component, which system component may include and actuating device and a travel simulator.