OBJECTIVE: To assess the usability and acceptance of activity tracking technologies by older adults. METHOD: First in our multimethod approach, we conducted heuristic evaluations of two activity trackers that revealed potential usability barriers to acceptance. Next, questionnaires and interviews were administered to 16 older adults ( M = 70, SD = 3.09, range = 65-75) before and after a 28-day field study to understand facilitators and additional barriers to acceptance. These measurements were supplemented with diary and usage data and assessed whether and why users overcame usability issues. RESULTS: The heuristic evaluation revealed usability barriers in System Status Visibility, Error Prevention, and Consistency and Standards. The field study revealed additional barriers (e.g., accuracy, format) and acceptance-facilitators (e.g., goal tracking, usefulness, encouragement). DISCUSSION: The acceptance of wellness management technologies, such as activity trackers, may be increased by addressing acceptance-barriers during deployment (e.g., providing tutorials on features that were challenging, communicating usefulness).