The effect of instructors and of using two different methods of teaching tennis on skill acquisition was investigated. Two hundred twelve subjects received beginning tennis instruction in either the traditional groundstroke (using a full grip) teaching method or the volley (using a graduated length grip) teaching method. To control teacher bias toward either method, each of the four participating teachers implemented both methods in different classes. All subjects were pre- and post-tested on the Broer-Miller Forehand-Backhand Drive Test. Results indicated that each teacher showed a preference for a particular teaching method, and that the effect of different methods cannot be statistically isolated because natural teacher variance cannot be separated from the main effect of the methods. It is suggested that future methodology studies employ several teachers and require that all teachers implement each method under investigation. (Authors/FG)