Writing, a complex organizational process that makes excessive attentional demands, can be frustrating for handicapped students. These students seldom complete a finished written product because t he y are usually trying to master the mechanical aspects of writing . Teaching the secondary-aged student with learning problems to use and unify writ ing skills into a finished product may be an initial step in helping them acomplish more difficult writing tasks. The purpose of this Research and Development (R & D) study was (a) to develop and validate an expert system which suggests teaching and management strategies for special education teachers and (b) to develop a curriculum which provides the special education teacher with an effective method for teaching students to produce a business letter. The development of Written Language Consultant (WLC) followed an R & D model which included the following stages: (a) product definition and design, (b) product prototype and progressive revision, and (c) product validation. The summative evaluation was conducted in six secondary special education classrooms. Thirty-two students participated in the study. A non-equivalent control group design with counterbalancing was used so that all teachers could use and evaluate WLC and all students could receive the treatment. The teachers completed a series of Likert-type questionnaires. The teachers' responses indicated that they agreed the information in the expert system knowledge base was valid, accurate , and practical. That WLC assisted teachers in successfully teaching these students to write a business letter was supported by the observed statistically significant differences between the experimental and control groups on parts A and B of posttest 1 after the initial treatment (p < . 01), the difference favoring the experimental group. Further supporting evidence was provided by the gains made by the control group after they received the treatment (pretest mean= 111, posttest mean= 375). An analysis of the students' performance by mastery level showed that once these students were taught the steps and procedures for writing a business letter they were able to produce a more acceptable product . When they were pretested, none of the students could write a business letter. After the students were taught to write a business letter by teachers using WLC, 21 of the 32 students (66%) could write a business letter at an 80% or better mastery level.