Former baseball star Jim Lefebvre (1983) claimed that hitting a baseball may be the most talked about but least understood skill in all of sports. Historically, hitting instruction has been based on intuitive thinking by "hitting gurus," rather than on scientific fact, which has contributed to this lack of understanding (DeRenne, Stellar, & Blitzbau, 1993). Compared to other sports, baseball has lagged in regard to the application of science to the development of the swing and training methodology. Although athletes and coaches have many hitting drills to choose from, few of these drills are grounded in science. A thorough understanding of the mechanics of the baseball swing is critical to formulating a sound training methodology. Therefore, the purpose of this article is to use previous studies to describe proper swing mechanics and to provide a few examples of drills that could be used to train these mechanics. However, the concepts of bat velocity and bat quickness must be considered before any discussion of swing mechanics. Recognizing the difference between these two, often misunderstood, concepts is a prerequisite for understanding the mechanics of the baseball swing.