This study examined individual and instructional predictors of the self-determination of students with disabilities, as measured by the "Arc's Self-Determination Scale" and the student version of the "AIR Self-Determination Scale." The general findings indicated that instructional, knowledge, and dispositional factors were stronger predictors of students' self-determination than personal predictor variables. In particular, self-efficacy and outcome expectancy scores, student-directed transition planning instruction, and students' preintervention transition planning knowledge were predictive of higher self-determination scores among students. (Contains 7 tables.)