The impact of portfolio assessment, specifically writing portfolios, on the norms of classroom assessment practices were studied in two English Language Arts classes in a middle class suburban high school in the Los Angeles (California) area. Data were gathered through observations and interviews, and the examination of 25 student portfolios, with student reflections and teacher comments, and 56 student compositions regarding portfolios. Students maintained working portfolios all semester, and selected items for permanent inclusion at the end of each semester. Portfolios counted heavily for grades in both classes. Portfolios in these classes met the qualifying criteria, but no impact on assessment practice was discernible. A single significant criterion was apparent in both classes, and that was completion of the assignment on time. Neither quality of work nor student growth appeared to be a consideration. Both teachers expressed discomfort regarding assessment. Students generally expressed favorable attitudes toward portfolios, but most (9 of the 11 interviewed) viewed the teacher as the primary variable in determining grades. Findings suggest that even expert instructors may lack the awareness, knowledge, and skills to participate in professional assessment practices, particularly with portfolios. One graph and one chart illustrate the discussion. (SLD)