The Second Biennial Mammalian Developmental Genetics Workshop will be held Bar Harbor, 11-15 September, 1991. This second meeting builds on the highly successful workshop held in Bar Harbor in 1989. Emphasis will be placed on the mouse as a model species, with sessions on mouse developmental mutations, imprinting, the genetic control of gametogenesis, the genetic control of morphogenesis, the genetic control of lineage determination and functional analysis of developmental genes through gene targeting. There will be an informal afternoon discussion of the Genetic Control of Implantation led by an invited speaker. Keynote presentations will focus on genes that control development in insects and mammals, and on the genetics of human development. Each session will begin with an invited 60 minute presentation providing an overview of the research problems and progress for the subject of that section. These overviews will be followed by three 20 minute more narrowly focused, complementary presentations. Participation of graduate students and postdoctoral fellows is encouraged.