Objective: Theory of Mind (ToM) is the ability to recognize mental states of oneself and that of other individuals (Parsons, 2002), which typically evolves with age in normative individuals (Hutchins, 2011). Research has shown that autistic individuals lack a developed ToM and that this triggers social impairments (Rajendran, 2013; Mathersul, 2013). The developmental progress of ToM in children on the spectrum is unknown; therefore, this study analyzed normative individuals and those on the spectrum to discover how the development of ToM in these two groups may differ with age. This study hypothesized that normative individuals would have a more advanced and developed ToM than those on the autistic spectrum, and thus score higher on the ToM Task Battery. It also hypothesized that the developmental trajectory of ToM would be slower for autistic individuals, but that the difference in ToM between autistic children and adolescents would be greater than that difference for the normative samples. Participants and Methods: Forty students participated in this study; 20 participants were on the autistic spectrum and 20 were normative. In addition, half were ages 6-10 and half were ages 11-15. Participants’ guardian was sent the informed consent forms and the ToM Inventory to fill out at home. All participants completed the ToM Task Battery in their school environment, either in the hallway or in a quiet spot of the classroom. Results: t-tests and ANOVAs revealed that normative individuals’ ToM (both guardian and student rated) was more advanced, developed normally, and stayed consistent, whereas autistic individuals’ ToM was undeveloped 9p < .001). When comparing younger and older children on the spectrum a significant improvement was observed (p = .002). Conclusions: The normative students were found to have a more developed ToM than the autistic students, this difference persisted even when compared to the higher functioning autistic students (n = 14; p = .002). Given these cross-sectional differences, it can be inferred that the autistic individuals' developmental trajectory is much slower than that of normative individuals; however, these results also indicate that autistic individuals may continue to develop their ToM with age.