This paper is concerned with the application of ideas inspired by developmental biology to the evolution of cellular automata rules using genetic programming. In particular, it is focused on so-called self-assembling patterns. The application of development in computing is reviewed, as is the evolutionary technique used in the paper—Cartesian Genetic Programming. A novel developmental algorithm, termed the Developmental Cellular Model is introduced, and five sets of experiments on various self-assembly problems are detailed and the results examined