This study investigated the effectiveness of portfolios as an instructional technique to reduce errors associated with test scoring by graduate students. Both the control and experimental conditions consisted of a lecture and demonstration on proper administration and scoring followed by a discussion. The experimental condition also required students to maintain a portfolio with completed protocols, which students reviewed prior to each ensuing practice administration. The experimental group demonstrated a significant reduction in scoring errors in comparison to the control group. These findings suggest portfolios are an effective instructional technique that can reduce errors made by graduate students when scoring tests measuring cognitive ability.