The purpose of this monograph is to serve as a primer for practitioners on the foundational theories of adult learning. It begins with an explanation two lenses through which learning theory is viewed: behaviorism and constructivism. The next section defines andragogy and delineates Knowles's five assumptions about adult learners. This is followed by a critique of Knowles's assumptions of andragogy through the eyes of foreign-born adult learners that examines the historic, political, and sociocultural contexts that influenced Knowles. The paper then presents several perspectives on transformative learning theory, describing theoretical approaches and criticisms of the theory. The next chapter discusses definitions, history, philosophical underpinnings, models, and criticisms of self-directed learning. A chapter on critical and postmodern theory explains their historical development, underlying philosophical tenets, and the differences between them. The next chapter examines race and its intersection with class and gender as it applies to learning theory and African Americans' learning processes; it discusses the tenets of Afrocentricity and its role in adult education. The concluding section considers the future of learning theory in adult education. Contains 166 references. (SK)