Data from the National Longitudinal Transition Study-2 (NLTS2) were used to examine (a) the aspects of self-determination assessed in NLTS2 and (b) measurement equivalence and latent differences across the 12 disability categories recognized in IDEA. Three of the four essential characteristics of self-determination - autonomy, self-realization, and psychological empowerment--were directly assessed. Measurement equivalence was established but there were significant latent differences 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 six collapsed disability groups, there were significant differences in the latent variances and limited mean level differences. Implications for future research and practice are discussed. [This article was published in "Exceptional Children," v80 n2 p221-235 Jan 2014 (EJ1048486).]