Premised on an interactive socialization as construction and internalization approach, physical activity socialization experiences related to peer interactions and associated affective responses in physical activity settings were explored among eight 11- to 12-year-old girls. Three possible physical activity choices (formal sport, informal physical activity, and exercise) were considered. Three methods of data collection were employed: observation, sociometric evaluation, and interview. Physical activity socialization experiences were found to be context specific both in terms of activity type (formal sport, informal physical activity, and exercise) and social situation (home and school). Boys in physical education classes appeared to be the major source of negative peer treatment, primarily by criticizing girls' physical skill performances and constructing them as subordinate to those of the boys. Positive or negative affective responses to peer treatment were reported to lead to the seeking or avoidance of future physical activity involvement. The type of attributions participants made for the negative treatment they received was related to their affective responses and subsequent desire to seek or avoid future activity.