Effective professional learning evaluation requires consideration of five critical stages or levels of information. These five levels, which are presented in this article, represent an adaptation of an evaluation model developed by Kirkpatrick (1959, 1998) for judging the value of supervisory training programs in business and industry. Kirkpatrick's model, although widely applied, has seen limited use in education because of inadequate explanatory power. While helpful in addressing a broad range of "what" questions, many find it lacking when it comes to explaining "why." The five levels in this model are hierarchically arranged, from simple to more complex. With each succeeding level, the process of gathering evaluation data requires more time and resources. And because each level builds on those that come before, success at one level is usually necessary for success at higher levels. The following five levels are presented: (1) Level 1: Participants' Reactions; (2) Participants' Learning; (3) Organizational Support and Change; (4) Participants' Use of New Knowledge and Skills; and (5) Student Learning Outcomes.