This study examines the external validities of the Davis measure of User Acceptance of Information Technology and the Doll and Torkzadeh measure of End-User Computing Satisfaction. To ensure that the generalizability of these instruments extends to discrete event computer simulation users, a confirmatory study was conducted. The instruments were tested for psychometric stability. This study provides evidence that the Doll and Torkzadeh measure of End-User Computing Satisfaction retained its psychometric properties when applied to users of discrete event computer simulation. The Davis measure of User Acceptance of Information Technology returned poorer scores on the gt indexes but the evidence did indicate the expected factor structure was supported.