This special issue of Psychology of Addictive Behaviors honors the life and work of a beloved friend, colleague, and mentor, Dr. Nancy M. Petry, who died on July 17, 2018 of breast cancer. At the time of her death, Dr. Petry was the editor of this journal. We were gratified to receive many submissions for this issue, resulting in an outstanding set of 24 selected articles. These articles span the multiple areas of addiction research to which Dr. Petry made key contributions, and this introduction highlights her work in these areas. The topic areas in this issue include behavior analysis and behavior pharmacology; contingency management-randomized controlled trials; contingency management-implementation and dissemination; demographic predictors of outcomes across multiple clinical trials; reinforcer pathology and decision making; and gambling. We can only imagine what great work Dr. Petry would have contributed in the future, but the research presented in this issue makes clear that her legacy and impact will continue to grow. (PsycINFO Database Record (c) 2020 APA, all rights reserved).