A cruise control device for a vehicle includes a regulator to regulate an actual speed with respect to a predefined setpoint speed, using a modular configuration including a regulator core module and at least one add-on regulator module. The core module ascertains a setpoint longitudinal force to be induced on the vehicle, based on a predefined setpoint speed and an ascertained actual speed, and to transmit the setpoint longitudinal force to the at least one add-on module. An add-on regulator module triggers actuators, e.g., drive and/or braking systems, based on the setpoint longitudinal force, e.g., for inducing the setpoint longitudinal force. Functions necessary for implementing various cruise control functions can be available centrally in the core module, whereas functions, used only in certain cruise control functions, may be in add-on regulator modules. Such modularity may reduce development effort and the need for hardware resources. Cruise control functions for off-road use may be implemented and added to traditional cruise control functions.