A modular plug connector in a strip-shaped design can be plugged together with a corresponding mating plug connector such as a printed circuit board plug connector. The modular plug connector has a plurality of plug connector modules which are arranged alongside one another and are connected mechanically to one another using mechanical connectors to form the strip shape. The plug connector modules each have a module housing, at least one plugging surface with at least one plugging contact and preferably at least one conductor or solder terminal for connection to a printed circuit board. The plug connector has at least two plug connector modules of different designs and an adapter plug connector module is provided therebetween.