Objective: To examine the impact Vitamin D has on cognition in the geriatric population. Method: Archival participant data from the Health First Aging Institute was utilized for this study. For the first part of the study, participant test scores on a general measure of neurocognitive functioning (MoCA) were correlated with Vitamin D levels from 300 older adults with a mean age of 80.61. For the second part of the study, participant test scores on the MoCA were compared pre- and post-treatment of low Vitamin D levels from 39 older adults with a mean age of 81.05. All participants underwent a medical evaluation, including Vitamin D lab-work and MoCA administration to obtain a baseline measure of their general neurocognitive functioning. In the second part of the study, an additional MoCA was administered after treatment for Vitamin D deficiency, as well as additional lab-work to verify treatment compliance. Participants with kidney problems, diabetes, and epilepsy were excluded from the study due to the impact these conditions have on Vitamin D concentrations. Results: There was a significant positive correlation between Vitamin D level and cognition, r(298) = .221, p < .0005., indicating higher scores on the MoCA were associated with higher levels of Vitamin D. Further, the paired samples t-test comparing participant test scores on the MoCA pre- and post-treatment of low Vitamin D levels yielded no significant results. Conclusion(s): While higher levels of Vitamin D have a positive impact on cognition, Vitamin D supplementation did not improve cognition in patients diagnosed with Vitamin D deficiency.