It is obvious that, all other things being equal, a player with a good vertical jump will have an advantage over a player with less jumping ability. There is more than one school of thought on the best way to develop this skill. Research by Brown et al. (1986) has shown that plyometric training can improve the vertical jump of high school male basketball players. The vertical jumping ability of 26 freshman and sophomore high school male players (average age = 15 years) was tested after 3 weeks (18 sessions) of practice. Two jump types were measured: a vertical jump in which the arms were free to be used in a double-arm swing (VJA) and one in which the arms were clasped behind the back (VJNA). The group was divided into 2 sub-groups: the "plyometric" group performed 3 sets of 10 repetitions (with 1 minute rest between sets) of depth jumping from a 45 cm bench. A total of 34 training sessions were undertaken over a 12-week period. The "control" group performed normal basketball training only. There was no difference between the 2 groups at the pre-training stage. After training, there was again no difference between the groups for the 'no arms' condition, and both groups had improved their vertical jumping ability. Both groups made significant improvements in their vertical jump when using the arms (21.3% and 17.7% for the plyometric and control groups respectively), but the improvement made by the plyometric group was significantly greater than that made by the control group. The findings support the use of plyometric-style training, in which the muscles are shortened immediately after being loaded eccentrically (i.e. lengthened). The results of this study suggest that 57% of the increase in jump ability is due to improvements in technique, while the remaining 43% is due to the plyometric training. Thus, while basketball practice alone is sufficient to improve vertical jump performance in high school boys, greater improvements may be generated by employing plyometric training techniques.