Research has indicated the surprising finding that random physical practice of a motor skill enhances the effects of long term skill acquisition more than blocked practice. The use of mental rehearsal coupled with physical practice has been shown to accelerate motor skill acquisition. In fact, mentally imaging a motor skill has also been shown to be better than no practice at all. Other researchers have found that some mental rehearsal strategies are better than others for maximizing performance. Unexamined is whether the way in which one images will impact successful physical practice (PP) when comparing random and blocked practice. Thirty subjects (M=29.6) were randomly assigned to one of five groups which included: 1)Blocked Mental Practice (BMP), Blocked Physical Practice (BPP); 2: BMP, Random Physical Practice (RPP); 3) Random Mental Practice (RMP), RPP; 4) RMP, RPP; 5) No MP, RPP. Three Bassin Anticipation timer tasks were utilized, each involving a particular speed (5 mph [SLOW], 13 mph [MEDIUM], 21 mph [FAST]). Either blocked mental practice or random mental practice followed a five minute recorded relaxation. Nine trials of mental practice were followed by 18 trials of physical practice, a sequence twice repeated. Blocked physical practice involved 18 repetitions of the same speed while random physical practice involved a varied presentation of each of the 3 speeds. A randomized 9-trial retention test of the three speeds was given after a 10 minute delay. The acquisition and retention data were analyzed with a 5 x 2 x 3 x 4 (Group x Gender x Speed x Trial Block) analysis of covariance, with repeated measures on Speed and Trial Block. There was a main effect of Gender, F(1,1)=5.83, p. <.05 and Trial Block, F(1,3)=3.504, p. <.05 on the medium speed trials. On the fast speed trials, there was a significant main effect of Group on the fast trials, with F(1,4)=8.056, p.<.001. Post hoc comparisons (Bonferroni) indicated that the BMP/ BPP group was significantly different from all of the other groups at the .05 level. This study indicated that the manner of mental practice was not important in two of the tasks. However, participants who received BMP and BPP performed significantly worse than all others on the retention task. There is the suggestion that the type of coupling of mental practice with physical practice becomes more critical when the task difficulty increases. Keyword(s): performance, physical activity, research