This study was undertaken to determine the effects of each of the production typewriting factors of keystroking, planning, and error correction on proficiency at typing business letters at two levels of instruction, at three levels of difficulty, and under three conditions. The conditions were designed to isolate the effect of each of the three factors on proficiency in typing business letters. A secondary purpose was to estimate the relationship between straight copy and letters, between letter conditions, and between speed and accuracy for straight copy and letters. The study involved 107 beginning typewriting students and 84 advanced typewriting students who were enrolled in six suburban high schools in Virginia. The same straight-copy timed writings and business letters were used in both the beginning and the advanced typewriting classes. The two 3- minute timed writings consisted of paragraph materials that had a stroke intensity of 6.0. The nine business letters also had a stroke intensity of 6.0 and consisted of three 150-word letters at low, medium, and high difficulty levels. / Ed. D.