Lay illness risk beliefs are commonly held philosophies about how risk works. These include beliefs that one’s personal illness risk is unknowable and beliefs that thinking about one’s risk can actually increase that risk. Beliefs about risk may impact risk behaviors and thereby subsequent health status. However, limited research examines the relation between lay risk beliefs and health behavior. This paper explores this possible relation. A nationally representative sample of adults (N = 1005) recruited from an internet panel were surveyed about lay risk beliefs and risk perceptions regarding diabetes and colorectal cancer, psychosocial factors (i.e., health literacy, need for cognition, locus of control), demographics, and current health behaviors (i.e., cigarette smoking, red meat intake, physical activity). In separate sets of regressions controlling for either demographics, psychosocial factors, or risk perceptions, lay risk beliefs remained significantly related to health behaviors. It may be important to consider how to address lay risk beliefs in intervention content and targeting in order to increase adaptive health behaviors and thereby prevent chronic disease.