The invention relates to a hydraulic braking system having a device for controlling brake slip, drive slip, and/or the driving stability of a vehicle. Among other things, such devices use pumps, valves, and reservoirs to control brake pressure in the wheel brakes in accordance with wheel slip occurring at the particular wheels. These components are in contact with each via a hydraulic circuit. The hydraulic circuit is built into a hydraulic block that has spaces for installing the components and channels for hydraulic contact. The invention makes possible a particularly compact and reduced-weight design of the hydraulic block and at the same time low manufacturing costs. For this purpose an advantageous layout and sealing of channels relative to each other and to the surrounding area is provided.