Background: The purpose of this study was to examine the effect of the followthrough on thrown ball velocity, potentially justifying inclusion of the followthrough in Roberton’s five critical components. Method: Seventy-eight University students participated in the overarm, dominant hand, throwing task, which involved throwing a standard tennis ball with maximum force three times. Each throw was filmed by two cameras placed behind and to the open side of the thrower to assess the throwing technique. The velocity of the throws was recorded with a radar gun. Results: Results indicated that, after accounting for the effects of gender, age, and throwing experience, there was a significant effect of followthrough level on throw velocity. Analysis of covariance also revealed a significant gender effect, with males throwing significantly faster than females. Results indicated the follow-through had the second largest impact on thrown ball velocity of all six components. Discussion: These findings provide preliminary support that the follow-through should be added to Roberton’s developmental levels. The inclusion of the follow-through component could assist teachers and coaches to facilitate learner and athlete development and could also improve the accuracy of throwing development assessment.