Showcased in this article is an interview with Carlo C. DiClemente, PhD, an internationally renowned health behavior researcher and codeveloper of the Transtheoretical or Stages of Change Model. In this verbatim interview transcript, later edited by the authors and interviewee, Dr. DiClemente, he provides practical information and frank commentary on the steps to follow and pitfalls to avoid in developing, implementing, evaluating, and disseminating efficacious programs for affecting the health and well-being of individuals and populations. A concluding section summarizes key lessons learned from the professional experiences of Dr. DiClemente and discusses implications for advancing health behavior intervention practice and research.