Summary: Osteoporosis is an increasing burden on individuals and health resources. The Osteoporosis Prevention and Self-Management Course (OPSMC) was designed to assist individuals to prevent and manage osteoporosis; however, it had not been evaluated in an Australian setting. This randomised controlled trial showed that the course increased osteoporosis knowledge. Introduction and hypothesis: Osteoporosis is a major and growing public health concern. An OPSMC was designed to provide individuals with information and skills to prevent or manage osteoporosis, but its effectiveness has not previously been evaluated. This study aimed to determine whether OPSMC attendance improved osteoporosis knowledge, self-efficacy, self-management skills or behaviour. Materials and methods: Using a wait list randomised controlled trial design, 198 people (92 female) recruited from the community and aged over 40 (mean age = 63) were randomised into control (n = 95) and intervention (n = 103) groups. The OPSMC consists of four weekly sessions which run for 2 h and are led by two facilitators. The primary outcome were osteoporosis knowledge, health-directed behaviour, self-monitoring and insight and self-efficacy. Results: The groups were comparable at baseline. At 6-week follow-up, the intervention group showed a significant increase in osteoporosis knowledge compared with the control group; mean change 3.5 (p <0.001) on a measure of 0-20. The intervention group also demonstrated a larger increase in health-directed behaviour, mean change 0.16 (p <0.05), on a measure of 0-6. Conclusion: The results indicate that the OPSMC is an effective intervention for improving understanding of osteoporosis and some aspects of behaviour in the short term.