First published in 1996. The field of behavior analysis began with the research studies of B.F. Skinner in the 1930s. In 1950, Keller and Schoenfeld published Principles of Psychology. It was the first text to present the basic principles of behavior analysis in a systematic fashion. While continuing to cite and describe the seminal articles in the field, in this book Leslie also includes clear presentations of new findings. The systematic presentation of these findings enables the author to provide laboratory based accounts of increasingly complex forms of human behavior, instead of plausible extrapolations which were the only option available at an earlier time. The Principles of Behavior Analysis does not sacrifice sweep for detail, and also does not sacrifice adequate presentation of basic principles for oversimplification.