In order to better understand the importance of adult learning theory to museum educators' work, and that of their profession at large, museum professionals must address the need for more adult learning research and practice in museums--particularly work informed by existing theory and work seeking to generate new theory. Adult learning theory begins with andragogy, but it does not end there. Guided by these ideas, and drawing from the author's work, this article highlights three adult learning theories and explores adult learning theory as a resource museum educators can use when designing and delivering training and professional development for front-line museum educators.