The Division of Developmental Biology of the American Society of Zoologists has sponsored, over the past several years, a series of annual symposia on the developmental biology of important phyla. The speakers at the symposia have reviewed the literature on the topic, discussed their personal contributions, and have speculated on future directions research might take. Those presentations have been well received by large audiences and have been published as collections of papers in a widely circulated journal, American Zoologist. At the 1977 winter meeting of the A.S.Z., a symposium which includes approximately 15 formal presentations and 2 roundtable discussions on the subject of the Developmental Genetics of the Mexican Axolotl will be held. More than 3 dozen mutant recessive genes have been recognized in the Mexican axolotl, Ambystoma mexicanum. These genes display a wide variety of phenotypes, most of which are exhibited at specific stages in the developmental cycles of the organism. These mutant phenotypes provide important experimental systems for the analysis by several laboratories of many areas of contemporary biological research. For example: gametogenesis and early development are being studied with a variety of maternal effect genes; the cytogenetics of amphibian development is being studied with the nucleolar mutant genes, organogenesis is being analyzed with model systems provided by the genes which specifically affect heart, eye, liver, brain or limb as the anemic and the quiver mutants, and various aspects of cell differentiation and cell interactions are being studied with several different pigment phenotypes.