The purpose of this study was to examine boys' perceptions of masculinity hierarchies in adventure physical education in relation to past experiences in sport-based physical education and their evolving views about physical activity in their lives. Theoretical principles of masculinity guided this study. Data were collected with 55 male high school students through 84 formal interviews, 200 e-mail interviews, and 135 ninety-minute class observations over 15 weeks. Data were analyzed using constant comparison with frequent member checks to facilitate trustworthiness. Three main findings emerged. First, boys described masculinity hierarchies in many past sport-based physical education classes as static and well-pronounced, which for many negatively impacted their perceptions of and engagement with physical activity. Second, boys described masculinity hierarchies in adventure physical education at Apex High School as shifting and narrowing, which stood in stark contrast to the inequitable status differentials in many sport-based physical education classes. Third, shifting and narrowing masculinity hierarchies resulted in significant positive outcomes for boys, most notably enhancing their orientations toward physical activity. Findings from this study suggest that physical education settings that produce shifting and narrowing masculinity hierarchies can enhance boys' perceptions of and engagement with physical activity both in and out of school.