Introduction—Alternative high school students are an underserved population of youth at greater risk for poor health behaviors and outcomes. Little is known about their physical activity patterns. Purpose—The purpose of this study was to describe 1) physical activity levels of students attending alternative high schools (AHS) in St. Paul/Minneapolis, MN and 2) compliance with wearing a physical activity accelerometer. Methods—Sixty-five students (59% male, 65% <18 years>old, 51% African-American, 17% Caucasian, 32% mixed and other) wore an accelerometer during all waking hours for seven days as part of the baseline assessment for a school-based physical activity and dietary behavior intervention. Accelerometer data was reduced to summary variables using a custom software program. Compliance with wearing the accelerometer was assessed by the number of days with ≥10-hours of data. Accelerometer counts/min, and minutes spent in moderate to-vigorous physical activity (MVPA) were calculated. Results—Students averaged 323±143.0 counts.min-1 and 51±25.5 min.d-1 of MVPA. Minutes of MVPA.d-1 were greater on weekdays compared to the weekend (52±27.3 vs. 43±39.7 min.d-1, respectively; p=0.05). However, students wore the accelerometer less on the weekends (weekdays=17.2±3.0, weekend=14.9±6.8 hrs.d-1). Expressing minutes of MVPA as a percentage of the number of minutes of available data, students spent approximately 5% of their time in MVPA on weekdays and weekends. Forty-five percent of students had 7-days of data, 51% had 4-6 days, and 5% had fewer than four days. On average, students wore the accelerometer for 17±3.2 hrs.d-1 (range 12.0-23.8 hrs.d-1). Conclusion—Compliance was high (95% of students provided at least four days of data) and physical activity was relatively low representing a vulnerable population in need of further study and intervention.