The New Mexico Portfolio Writing Assessment for grades 4 and 6 (optional for grade 8) is to be conducted in the 1991-92 school year, with a call for "best piece" in April of 1992. All students in New Mexico in grades 4 and 6 will participate. This manual provides instruction for procedures to be followed in the school year. Guidelines should be observed by each classroom teacher charged with conducting the assessment in order to assure the validity of the results. The assessment is to be conducted in a classroom setting. Each student is to have a portfolio to store written materials until the best piece is submitted. The scoring guide in this manual contains a practice prompt that teachers may use with students while explaining the prompts and scoring procedures. There are three prompts at each grade level that are required for developing and storing in the students' portfolios. For each grade, a prompt is supplied for narrative, descriptive, and expository writing. In the spring of 1992 students and teachers will select the "best piece" for each prompt, although a best piece will only be sent out for scoring for one of the prompts. Final drafts of best pieces should remain in the portfolio to be passed to the teacher of the next school year. Students will receive individual holistic scoring reports, and the school will receive overall results. Numerous student writing samples are provided. A 21-item bibliography is included. (SLD)