A lane changing assistant for motor vehicles, having a speed control system and a surroundings sensor system for recording the traffic environment including the traffic in an adjacent lane, having a decision device for deciding whether a lane changing request of the driver is to be accepted, and having a command device for issuing an acceleration command to the speed control system in the case of a lane changing request, wherein a recognition device is developed to recognize a window for swinging into the adjacent lane without danger, in the light of the data of the surroundings sensor system; and the command device is developed to compute an acceleration strategy adjusted to the window, including a point in time for the beginning of the acceleration.