This article provides an overview of adult learning theory, focusing on the theories covered in this issue of New Directions in Adult and Continuing Education. In offering a brief synopsis of each article and reflecting on the ways adult learning theories have evolved since the first update was published in 1993, this article explains several themes that characterize that evolution: (1) the continued importance of foundational learning theories, (2) the diversity of learners and learning, and (3) the presence of technology in today's world. A combination of these themes is present in every article, which characterizes the current state of the field of adult learning theory.