Content: - Introduction - An Expanded Vision of Stroke Analysis - Nine Principles of Biomechanics - Stroke Examples Summary: Tennis coaches can help maximize player performance by employing an interdisciplinary approach to qualitative analysis. Biomechanics is one of the most important sport sciences for evaluating and diagnosing tennis techniques. Biomechanical knowledge can be organized into nine principles for application in the qualitative analysis of tennis strokes. For more examples of qualitative analysis of tennis strokes see Knudson (1999) or Knudson and Morrison (1997).