It has become apparent through the work of many researchers and practitioners that adults learn differently than their younger counterparts in the educational system. This is especially important to those educators teaching in colleges and universities in the sciences. Biology education in the post-secondary setting is inundated with teachers who know biology backward and forward but lack the skills to effectively teach that knowledge to others. By applying the theories of andragogy, transformational learning, and experiential learning, and by integrating practices of self-directed learning and critical reflection, we can improve the effectiveness of biology education in American colleges and universities.