This project was undertaken to develop a Workplace Physical Activity Assessment Tool to evaluate workplace physical activity programs based on a standard of best practices indicated in the literature and by key stakeholders. The development of the Assessment Tool was structured on an ecological model for health and physical activity promotion and an occupational health and safety audit instrument. The project included a review and synthesis of pertinent literature, expert and stakeholder reviews, interrater reliability appraisals, and workplace consultations over three distinct study phases. The Assessment Tool was received positively by the expert reviewers (i.e., academics, policy makers, and practitioners) and revealed generally high interrater reliability. The Workplace Physical Activity Assessment Tool can be used to plan, implement, and evaluate physical activity programs in the workplace. Recommendations for future research are identified.