Objective: To derive an empirical taxonomy of osteoprotective stages using the Precaution Adoption Process Model (PAPM) and to identify the predisposing factors associated with each stage. Methods: An anonymous survey was completed by 504 undergraduates at a Midwestern public university. Results: Cluster analytic findings indicate that only 2 osteoprotective stages exist in young adults: less engaged and engaged. These two groups were best distinguished by health motivation, sex, a perceived barrier to exercise, and exercise self-efficacy. Conclusion: Fine-grained stages of osteoprotective behavior are not apparent in young adults, suggesting that the PAPM may not be useful for explaining the adoption of osteoporosis precautions.