Developmental pattern formation allows cells within a tissue or organ to coordinate their development and establish cell types in relationship to one another. To better characterize the developmental patterning events within one organ, the C. elegans hindgut, we have analyzed the expression pattern of several genes using green fluorescent protein-based reporter transgenes. In wild-type animals, these genes are expressed in subsets of hindgut cells rather than in individual cell types. In mutant animals, we find that some, but not all, genes expressed in cells with altered development exhibit a corresponding alteration of gene expression. The results are consistent with a model where a combination of factors contribute to each cell's fate, and address how developmental information converges to specify cell types.