Objectives The purpose of this study was to examine the efficacy of Harris and Harris' (1984) concentration grid exercise, an exercise proposed to enhance concentration and visual scanning speed [Harris, D.V., & Harris, B. L. (1984). The athlete's guide to sport psychology: Mental skills for physical people. New York: Leisure Press]. Method Twenty-eight male collegiate soccer players were assigned to either a 9-week concentration grid training condition or a control condition. Concentration grid training consisted of 9 weekly meetings with an experienced sport psychologist with practice assignments in between sessions. During the first, fifth and final weeks of the experiment all participants completed a battery of concentration tasks (a visual search task, a video observation task and a concentration grid). Results A series of MANOVA's and ANOVA's indicated no significant interaction effects indicating that the concentration training group did not improve to a greater extent than the control group in any measure of concentration. Conclusions The findings highlight the need for further research examining the efficacy of the concentration grid exercise using different training protocols and different dependent measures. In addition, the results also indicate support for sport psychologists who have urged caution with the use of the concentration grid exercise in applied sport psychology.