The purpose of this study was to determine the effect of the Macmillan Tutorial System when used as a supplement to regular classroom instruction in beginning reading. The experimental subjects were first grade children who ranked in the lower third of the distribution scores on the Macmillan Reading Readiness Test or who, in the opinion of their teachers, were not progressing at a satisfactory rate. One hundred subjects were tutored in the Macmillan Reading Program as a supplement to regular classroom instruction for fifteen minutes a day from the end of February to the beginning of June. The control group of 100 students were not tutored. Scores on the Word Reading Test, the Paragraph Meaning Test, and the Word Study Skills Test of the Stanford Achievement Test Primary I Battery were used as pre- and post-tests to determine gain in reading achievement during the experimental period. Scores on the Macmillan Reading Program Mastery Tests were used to determine reading achievement. The data examined showed that the students who were tutored responded by progressing more rapidly and scoring higher on achievement tests than did the matched control students. (Author/WR)