This research investigated the effects of aquatic training on the swimming performance of 126 children, ages 2.5 to 5.5 yr., over 8 mo. Two groups of children were enrolled in an aquatic training program. Group 1 were returning program participants at the beginning of this study, and Group 2 were new participants. The control children (Group 3) received no aquatic training during the research. Subjects performed six categories of swimming tasks at three points in time--1st mo., 4th mo., and 8th mo. The categories were Locomotion: Front, Locomotion: Back, Kicking, Entry: Jump, Diving, and Ring Pick-up. A 2 X 3 X 2 X 3 (sex X group X age X time) repeated-measures analysis of variance procedure showed that returning participants performed each category of swimming tasks at a more advanced level than the other groups at each time of measurement. New participants after training performed five of the categories of tasks at a more advanced level than the control group. Amount of training significantly influenced swimming, and training effects were task-specific when data were interpreted in terms of specific movement characteristics.