Competitive swimmers were asked to swim at a constant velocity (v) for short distances. They wore a collar to which was attached a fine non-elastic steel wire. The wire passed over two wheels of a device attached to one end of the pool. One wheel generated an impulse for every cm of forward movement and another wheel produced an electrical signal which was directly proportional to V. Measurements of distance and time were begun at definable points in the stroke cycle and were discontinued at the end of a predetermined number of strokes. In all of the four competitive strokes, front and back crawl, butterfly, and breaststroke, the V increased as a result of increasing the stroke rate (S) and decreasing the distance per stroke (d/s). In the front crawl, the male and female swimmers who achieved the fastest V had the longest d/S at slow S. The faster male swimmers also had greater percent decrease of the d/S at their maximal V than did the less skilled persons. The back crawl was similar to the front crawl except that maximal S and V were less. Increases of V of the butterfly were related almost entirely to increases in S. Except at the highest V, d/S was decreased somewhat. In the breaststroke increased V was also associated with increasing S, but the d/S decreased much more than in the other stroke styles. Fluctuations of velocity during the stroke cycle were least in the front and back crawl (+/- 15--20%) and greatest in the butterfly and breaststroke (+ 45--50%). The results were compared to the S observed and the values for V and d/S calculated for a large group of swimmers competing in the 1976 U.S. Olympic Trials. The implications of the findings for coaching swimmers are discussed.