Although ball speed is considered a measure of success in baseball pitching, little is known about the relationship between ball velocity and pitching mechanics. Investigation of this relationship has been limited, and the studies carried out have varied in methodology. Three-dimensional, high-speed (240 Hz) video data were collected on fastballs from 54 collegiate baseball pitchers. Kinematic parameters related to pitching mechanics and resultant kinetics on the throwing shoulder and elbow were calculated. Multiple linear regression analysis was used to relate ball velocity and pitching mechanics. Ball velocity averaged 35 m/sec (79 mph) for the 54 college pitchers. Nearly 70% of the variability in ball speed can be explained by a combination of 10 parameters related to pitching mechanics. Body mass and 9 temporal and kinematic parameters related to pitching mechanics combine to account for 68% of the variance in ball velocity for a collegiate population of athletes. These variables can be manipulated via mechanical changes and sport-specific training to affect ball velocity. The results of the study can be used to increase ball velocity while at the same time minimizing stresses on the throwing arm elbow and shoulder. Improved training programs can begin to be developed based on these data.