Objectives: To evaluate the effectiveness of an online chronic disease self-management program for South Australia residents. Method: Data were collected online at baseline, 6 months, and 12 months. The intervention was an asynchronous 6-week chronic disease self-management program offered online. The authors measured eight health status measures, seven behaviors, and four utilization measures; self-efficacy; and health care satisfaction. Results: Two hundred fifty-four South Australian adults with one or more chronic conditions completed baseline data. One hundred forty-four completed 6 months and 194 completed 1 year. Significant improvements ("p" less than 0.05) were found at 6 months for four health status measures, six health behaviors, self-efficacy, and visits to emergency departments. At 12 months, five health status indicators, six health behaviors, self-efficacy, and visits to emergency departments remained significant. Satisfaction with health care trended toward significance. Discussion: The peer-led online program was both acceptable and useful for this population. It appeared to decrease symptoms, improve health behaviors, self-efficacy, and reduce health care utilization up to 1 year. This intervention also has large potential implications for the use of a public health education model for reaching large numbers of people. It demonstrates that an Internet self-management program, which includes social media, can reach rural and underserved people as well as be effective and reduce health care costs. If this intervention can be brought to scale, it has the potential for improving the lives of large numbers of people with chronic illness. It represents a way the medical care and public health sectors can interact. (Contains 4 tables and 1 figure.)