Interest in measuring physical activity via motion sensors within physical education by researchers and practitioners has become apparent.  However, with the increased interest and application, it becomes clear that empirical comparisons of association and agreement between motion sensors be undertaken.  The aims of this study were to examine: (a) the association and agreement between the Yamax SW-701 and Walk-for-Life LS-2505 pedometers in measuring steps during lab and physical education; (b) the association and agreement between the LS-2505 pedometer and BioTrainer (BioT) Pro bi-axial accelerometer, and LS-2505 pedometer and RT3 tri-axial accelerometer in measuring physical activity time during physical education; and (c) the relationship between pedometry and BioT, and pedometry and RT3 during physical education.  Data were collected on 231 (12.79±1.10 yrs., 20.46±4.11 kg/m^-2) participants in fifth- through eighth-grade physical education and 26 (13.35±.75 yrs., 28.34±4.25 kg/m^-2) seventh- through eighth-grade students in an exercise science laboratory.  Physical activity measures consisted of pedometer steps per minute (steps/min.^-1), pedometer activity time (LS-2505 only), BioT counts and activity time using a 15-sec. epoch interval, and RT3 counts and activity time using a 1-sec. epoch interval (i.e., VMag).  Physical education physical activity data were collected with the following parameters: 3 schools, 5 teachers, 18 intact classes, and 9 content types.  Laboratory activity data were collected on a Quinton treadmill at walking speeds of 4 km/h^-1, 6 km/h^-1, and a self selected brisk walking speed for a total treadmill time of 8 minutes.  Pearson r correlation coefficients, Bland-Altman plots, and one-sample t-tests were the applied statistical techniques.  Alpha was set at .01.  SW-701 and LS-2505 pedometer steps/min.^-1 relationships were strong and significant in lab (r=.80) and physical education (r=.98).  Pedometer step/min.^-1 difference (SW-701 – LS-2505/n) in lab was not significantly different from 0 (M_d=1.04±3.95, p=.19), but a significant step/min.^-1 mean difference in physical education existed (M_d=7.81±5.36).  Accelerometry measured activity time (min.) demonstrated a strong and significant relationship with LS-2505 pedometer activity time (BioT r=.89; RT3 r=.89).  In comparison with accelerometry (BioT M_d=-4.60±3.39 min., p≤.01; RT3 M_d=-7.35±3.12 min., p≤.01), LS-2505 pedometer activity time overestimated physical education physical activity time.  The relationship between pedometry step/min.^-1 and accelerometry measures of counts and activity time were strong (r=.86-.93; p≤.01).  In conclusion, pedometry and accelerometry measures demonstrated strong and significant associations, but during physical education agreement between SW-701 and LS-2505 pedometer steps/min.^-1 and accelerometry and LS-2505 activity time indicate that instruments may not give researchers and practitioners similar absolute activity data.