A series of studies investigated the development of infants' understanding of the containment function of certain objects. In Experiment 1, infants' absolute preference for looking at either a can or a tube was tested. No preference was found. Two measures were used in Experiments 2 and 3. One assessed infants' looking response or gaze behavior directed to videotaped sequences of pouring behavior which were designed to establish habituation and reveal differences between a can and a tube. Another measure assessed infants' ability to imitate the dropping of cubes into a cup. In Experiment 2, infants 14 months of age were contrasted with 20-month-olds; results replicated a prior finding that older but not younger infants demonstrate an understanding of containment. The main study, Experiment 3, examined whether the understanding of containment could be acquired by 14-month-olds who were given training. A total of 50 infants were randomly assigned to 5 training conditions. These involved 4-week training with, respectively, container and cube; container only; tube only; ball only; and a laboratory visit conducted for the purpose of testing short-term training. Only one condition was effective in leading to the development of an understanding of containment. Infants 14 months old who played with both cans and tubes in their home for 1 month performed in both tests in a manner similar to that of untrained 20-month-olds. (Author/RH)