After the introduction of uprooted trees to their environment, the behavior of 28 socially housed, laboratory chimpanzees (Pan troglodytes) was studied for five months. Subjects used the tree during 41.9% of the data points collected during the first day trees were introduced. Thereafter, the mean for tree use dropped to 3.5% and remained fairly consistent. Immature subjects used the trees significantly more than did adult subjects, as measured by the Mann-Whitney U-test. No sex difference was detected. The trees elicited a variety of species-appropriate behaviors. Increasing the similarity between the behavior of captive and wild chimpanzees can be viewed as promoting the psychological well-being of the captive animals.