There have been well-documented increases in overweight and obese children, sedentary lifestyles (Mokdad et al., 1999), and an increased prevalence of hypokinetic disease over the past 20 years (CDC, 1997). Physical Education's role in this public health effort has grown increasingly important in combating physical inactivity. However, little evidence exists that illustrates the actual contribution of Physical Education to the overall physical activity (PA) patterns of children. Purpose: To determine the contributions of Physical Education to the daily pedometer-determined PA of fourth and fifth grade children by examining children's PA levels on Physical Education vs. non-Physical Education days. Methods: Fourth (n = 408) and fifth (n = 421) grade children (N = 829) from six elementary schools (five districts) from a Southwestern US state wore a pedometer (Yamax Digiwalker SW-200) for 5 consecutive school (week) days. Boys (n = 400) and girls (n = 429) were 9.56 (± .67) years old, with the following ethnic background: Caucasian (44%), Hispanic (36%), African-American (10%), Native American (5%), and Asian/Pacific Islander (4%). Participants' mean BMI (measured using a digital scale and stadiometer) was 19.34 (± 4.15). T-tests and ANOVA tests were used to compare physical activity levels across sex and BMI. Analysis/Results: Select findings illustrate that participants were significantly more active on Physical Education days compared to non-Physical Education days (t (553) = 6.83, p < .01). Boys accumulated 13,892 (± 4,816) steps per Physical Education day compared to 12,877 (± 4,274) steps per non-Physical Education day. Girls accumulated 12,234 (± 3,998) and 10,624 (± 3,436) steps per Physical Education and non-Physical Education day, respectively. Children who had multiple days of Physical Education per week (n = 506) accumulated 12,305 (± 3,959) steps/day compared to children who had Physical Education one day (n = 297) per week (11,521 ± 3,436), which was significantly greater (t (782) = -2.78, p < .01). Children classified as overweight (n = 177) or at-risk of being overweight (n = 127) according to age and sex specific BMI cut points (CDC, 2008) accumulated an additional 1,137 and 711 steps on Physical Education days, respectively. Conclusions: Physical Education provides increased opportunities for PA for all children, regardless of sex and BMI. These findings support the continued drive toward ensuring quality school Physical Education programming as a key factor for reducing physical inactivity and national obesity trends in children and youth. Keyword(s): exercise/fitness/physical activity, obesity issues, physical education PK-12