The effects of specific play apparatus experience on a test of upper body muscular endurance was investigated among a group of children 4-6 years old. Both the control and experimental group consisted of 45 subjects randomly selected on the basis of age from two private day care centers situated in the same community. The two groups were of similiar socioeconomic status. Each group had a 30 minute free-play period and a 30 minute structured-play period of motor development activities 5 days a week for 10 weeks. The only difference between the treatment of the two groups was in the playground equipment available. The experimental group had more equipment of the "upper body" movement variety (e.g., horizontal ladders) than did the control group. Subjects were pre- and post-tested for upper body muscular endurance using the straight-arm hang. Results indicated that specific playground experiences, as provided by a well equipped play environment which had overhead climbers and ladders available, was a contributing factor in the increased muscular endurance performance of the experimental group. (JM)