Girls in the United States are at high risk for inactivity and resultant overweight or obesity. Perceived barriers to physical activity are critical factors for health care professionals to consider when intervening with this population to increase physical activity. This descriptive study identified barriers to physical activity reported by girls in middle school. Participants were recruited from two middle schools in the Midwest. Using a Likert-type scale, a total of 77 ethnically diverse girls, ages 11 to 14, responded to 23 items representing barriers to physical activity participation. Mean scores and percentages were computed for each barrier statement. The top barriers to physical activity that emerged for the girls in this investigation were "I am self-conscious about my looks when I exercise" and "I am not motivated to be active." Strategies that health professionals can use to counsel girls of this age in overcoming barriers to physical activity are presented. This health-related information can enhance anticipatory guidance to girls.