In developmental biology, modeling and simulation play an important role in understanding cellular behavior. This article includes a review of the general models of development that are based on cellular interaction. Inspired by these models, we suggest a simple language, the Cell Programming Language (CPL), to write computer programs to describe this developmental behavior. These programs are an estimate of the minimal information needed to model realistically such developmental systems. Using these programs, it is possible to simulate and visualize cell behavior. We have employed CPL to model the following: aggregation in cellular slime mold in response to a chemotactic agent, cellular segregation and engulfment due to differential adhesion, and precartilage formation in vertebrate limbs. We believe CPL is a useful tool for developing, understanding, and checking biological models.