As curricula to improve medical students' attitudes toward people with disabilities are developed, instruments are needed to guide the process and evaluate effectiveness. The authors developed an instrument to measure medical students' attitudes toward people with disabilities. A pilot instrument with 30 items in four sections was administered to 342 medical students. Internal consistency reliability and factor analysis were conducted. The Cronbach's alpha coefficient was 0.857, indicating very good internal consistency. Five components were identified: comfort interacting with people with disabilities, working with people with disabilities in a clinical setting, negative impressions of self-concepts of people with disabilities, positive impressions of self-concepts of people with disabilities, and conditional comfort with people with disabilities. The instrument appears to have good psychometric properties and requires further validation.