Vitamin D is an essential nutrient and a secosteroid hormone that regulates many physiologic processes beyond calcium and bone homeostasis. These "extraskeletal" effects are impacted by the circulating levels of the storage form of vitamin D, 25-hydroxyvitamin D3. Levels of vitamin D can be detected after completing a simple 25(OH)D blood test. Vitamin D deficiency (< 30 ng/mL) is associated with a higher risk of many chronic diseases including, but not limited to, fourteen types of cancers, type 1 and 2 diabetes mellitus, obesity, cardiovascular disease, hypertension, stroke, and asthma. This article explores the association between vitamin D deficiency and the burden of chronic diseases in West Virginia.