Wearable Activity Trackers (WATs) are often ascribed the ability to reduce health risks by promoting physical activity and healthful eating habits. However, research has shown that their use does not always lead to behavior changes. Using the affordance lens, this study investigates how WATs’ material features facilitate behavioral outcomes, as users interpret WATs in light of their personal health-related goals. Using narrative interviews with twenty-five WAT users, we found two catego-ries of affordances—learning affordances and behavior-focused affordances—leading to three behavioral outcomes: behavior change, compliance change, and remaining with the status quo. Moreover, we identified four types of users (based on their goal configurations) that actualized different affordances and showed different behavioral outcomes. While some types of users fundamentally changed their daily routines as a result of using WATs, others simply complied with technology cues or did not change their behavior at all. Our results have several implications for re-search on WATs and WATs’ design.