One goal of computer-based instruction in writing is to help students to edit their compositions, particularly those compositions written on a word processor. This can be accomplished by a complete editing program that would contain the full set of mechanics rules--capitalization, punctuation, spelling, usage--appropriate for the grade level of the intended user. The specific rules that students would practice could be decided in three ways: (1) the student would choose from a menu those rules that need to be practiced, (2) the teacher would choose those rules the student should practice, and (3) the computer would assign students to the appropriate rules on the basis of pretest scores. After content for practice is assigned or chosen, the student is given the option of reviewing the rules to be practiced. Following this optional rule review, students receive three kinds of practice: choice, correction, and dictation. The choice section provides basic practice in discriminating the correct application of the rules under study. The correction section begins with instruction on the why and how of editing--with specific text-editor procedures on the computer. For the dictation section of the program, the computer presents sentences orally, and the student types in the sentence. Each section provides the student with feedback and evaluation. If the student does not meet the criterion for the correct responses in each section, instruction is terminated and the student goes back to the teacher for additional help. (HOD)