Gary Kielhofner, DrPH, OTR, FAOTA (1949–2010), developed, with Janice Burke, the Model of Human Occupation, one of the most widely used theories in occupational therapy research and practice. This model presented practitioners with a conceptual framework and practical tools to guide their assessment and reasoning process, effect change, and measure the impact of their intervention. He was a passionate and devoted mentor to and collaborator with numerous colleagues. Kielhofner received many of the profession’s highest awards and honors, including AOTA Fellow (1983), induction into the AOTF Academy of Research (1984), the AOTF A. Jean Ayres Award (1989), and the Award of Merit (2011). Read Kielhofner’s In Memoriam.