Pedometer accuracy for steps and activity time during dynamic movement for youth with intellectual disabilities (ID) were examined. Twenty-four youth with ID (13 girls, 13.1 +/- 3.2 yrs; 11 boys, 14.7 +/- 2.7 yrs) were videotaped during adapted physical education class while wearing a Walk4Life 2505 pedometer in five locations around the waist. Researchers viewed each videotape and recorded observed steps and activity time. Observed findings were compared with pedometer recorded steps and time. On average, pedometer registered steps were underestimated by approximately 14% +/- 16.5%, whereas pedometer registered time was overestimated by approximately 8.7% +/- 21.8%. The findings indicate that the accuracy of pedometers may be compromised during dynamic movement for youth with ID.