We introduce a new model for objects which can move around on a cellular grid. The model consists of two phases, the movement phase and the con ict resolution phase. In the movement part of the description objects specify their desired direction. The con ict, which occurs when alternative objects want to move to the same free cell, is resolved in the con ict resolution part. The cellular description language CDL was extended to CDL++ in order to describe moving objects. This extension is automatically converted into a two{phased CDL program.