The authors used data from the National Longitudinal Transition Study-2 (NLTS2; SRI International, 2000) to examine the aspects of self-determination assessed in NLTS2 and measurement equivalence and latent differences across the 12 disability categories recognized in the Individuals With Disabilities Education Act (IDEA; 2004). NLTS2 included a direct assessment with items representing 3 of the 4 essential characteristics of self-determination--autonomy, self-realization, and psychological empowerment. The authors established measurement equivalence, but significant latent differences occurred across specific disability groups. Students with high-incidence disabilities (learning disabilities, emotional disturbances, speech or language impairments, and other health impairments) showed similar latent means and variances, as did students with sensory disabilities (visual and hearing impairments) and cognitive disabilities (autism, multiple disabilities, and deaf-blindness). Students with intellectual disability, traumatic brain injury, and orthopedic impairments could not be collapsed with any other group. Across the 6 collapsed disability groups, significant differences existed in the latent variances and limited mean level differences.