Donald M. Baer (October 25, 1931 – April 28, 2002) was an American psychologist who contributed to the science of applied behavior analysis and pioneered the development of behavior analysis at the University of Kansas and the University of Washington. Baer is best known for his contributions at the University of Kansas. Throughout his career, he published over two hundred articles, books, and chapters on various psychological issues. Some of his most noteworthy contributions include literature on behavior-analytic theory, experimental design, and early childhood interventions. Baer received numerous awards during his lifetime which acknowledged his innovation and dedication to his field of research.