Many studies have found support for the contextual interference effect in motor skill learning using laboratory tasks. There has, however, been less support for the effect with non-laboratory tasks. The purpose of the present study was to investigate the impact of two possible limitations of non-laboratory applications of the contextual interference effect: hand dominance, and number of acquisition practice trials. Forty-eight participants performed three different throwing tasks with tennis balls: (1) Overhand toss, (2) Underhand toss, and (3) Bounce task, during acquisition and retention sessions. Participants also performed a “toss-bounce-bank” task during a transfer session. For each task, the goal was to toss the ball into a plastic target from a distance of 12 feet. There were 90 acquisition trials and 15 retention trials of each task, and 15 trials of the transfer task. The number of acquisition trials was twice as many as in Wiley (2000). Half of the participants performed the tasks with their non-dominant hand; the other half used their dominant hand. During acquisition, half the participants performed the tasks under a blocked practice schedule, and half performed under a random practice schedule. During retention, four groups were created whereby half of the participants remained in their original acquisition schedule and the other half were switched to the opposite schedule. Data was recorded as either a hit or miss, divided into 15-trial blocks for evaluation, and analyzed by means of ANOVA procedures. Results indicated a significant interaction during acquisition, whereby low levels of contextual interference (i.e., blocked practice) produced better performance with the dominant hand, but high levels of contextual interference (i.e., random practice) produced better performance with the non-dominant hand. However, this interaction was not significant during retention. During acquisition and retention, performance of the overhand toss was best with the dominant hand, and worst with the non-dominant hand. Performance of the underhand toss and the bounce task was relatively independent of hand dominance. Finally, the additional acquisition trials in the present study, compared to Wiley (2000), did not appear to enhance the contextual interference effect.Keyword(s): performance, research