A computer simulation of psychoeducational decision making was used to study the extent to which the assessment and decision-making process differs for different kinds of students, the extent to which naturally-occurring pupil characteristics (appearance, sex) influence diagnostic outcomes, and the extent to which decision makers perceive different assessment information and pupil characteristics as influencing their decisions. The decision-making process did not differ as a function of differences in referral information. While SES, sex and physical appearance did not affect outcome decisions, the nature of the reason for referral did. Scores on achievement tests, intelligence tests, and the disparity between the two were rated as having the greatest influence on the eligibility, classification, and prognostic decisions that were made. Decision makers said they were not influenced by naturally-occurring pupil characteristics.