This chapter aims to the study of behavior, with special emphasis on the place of genetic procedures, and of the genetic code, in the study of the neural coding and processing of stimulus information. The rediscovery of Mendel’s work at the turn of the century set the stage for one of the most concerted efforts in all science. It specified a new subject matter, the most appropriate subjects for experimentation, and a method of investigation. The importance of the genetic method in the study of learning has been recognized ever since Tryon’s massive genetic study of maze learning in rats. An effective behavioral genetic investigation of learning memory must deal with the complexities of both the genotype the learning process. The investigations that quickly followed in Tryon’s trail alerted the field to the shortcomings of a long-standing typological mode of thinking in psychology and pointed to the need to replace it with more appropriate concepts of hereditary and environmental individuality.