Ir Genes and Ia Antigens features papers that were presented at the Third Ir Gene Workshop held in Asilomar, California, December 13-16, 1976. The book is organized into seven parts that correspond to the seven sessions held during the workshop. The first session focused on the definition of the I-E and I-C subregions, and the mapping and cellular expression of complementing Ir genes. The second session included papers on the expression of gene products of the I region. The third session covered two major areas: (1) the biochemical characterization and primary structure of la antigens; and (2) the possible carbohydrate nature of la antigenic determinant. The studies presented in the fourth session focused on the role of I-region gene products in cellular interactions. The fifth session discussed the "recognition" functions controlled by the I region of the major histocompatibility complex (MHC). The sixth session featured papers on la-containing T cell factors. Finally, the seventh session examined the properties of T-cell antigen receptors.