Description: The first purpose of this study was to develop and validate the Inventory of Opinions About Persons with Disabilities (IOPD). The IOPD was developed to collect preservice early childhood educators’self-report data related to inclusion. A total of 332 participants enrolled in graduate programs in a college of education served as the validation sample. After validation and revision of the IOPD, the researcher used the instrument to investigate preservice early childhood educators’ beliefs, attitudes, and knowledge about students with disabilities and their inclusion in general education classrooms. Data were collected from 172 participants from 10 universities in Texas during their student teaching/final intern semesters. This research demonstrated that an instrument, the IOPD, could be developed to effectively measure preservice early childhood educators’ beliefs, attitudes, and knowledge about the inclusion of children with disabilities in their classrooms. The participants reported positive self-perceptions (mean = 2.0388) about their beliefs and attitudes toward inclusion. However, the participants reported less positive attitudes about training (mean = -.09884). Discriminant function analyses indicated a negligible statistical effect for type of program (professional development school or traditional) and a statistically significant effect for preferred classroom setting (non-inclusive, special education, inclusive). Further research with the same participants or similar ...