Researchers examined the impact of an extended time accommodation on appropriate classroom behavior and rate of work completion for 33 children with attention-deficit/hyperactivity disorder (ADHD). Participants received standard (30 min) or extended (45 min) time to complete seatwork in a within-subject, crossover design study. Appropriate behavior (i.e., rule-following behavior) and rate of problems completed accurately per minute were compared across conditions. Children completed significantly more problems correctly per minute when given standard time compared with extended time; however, no difference in appropriate behavior was found between the two conditions. Appropriate behavior over time was examined by segmenting each condition into time intervals. Analyses indicated that children's appropriate behavior significantly decreased over time in both conditions. The implications of these findings are discussed. (Contains 4 tables.)