There is growing interest in improving population health by multi-sectorial partnerships that address the determinants of health. The Leeds, Grenville and Lanark District Health Unit worked with some 80 other community agencies to form the Lanark, Leeds and Grenville Health Forum in the spring of 2000. The goals of this Health Forum were to evaluate the determinants of health of the population over a five-year period, identify activities within an overall Health Improvement Plan to address these determinants, pursue ongoing resources for interventions, assess their impact on health, and modify plans and activities accordingly. The Health Forum identified that their region had increased mortality rates from cardiovascular disease and cancers compared with the rest of Ontario. The local district health unit offered three possible determinants to explain this: socio-economic determinants (residents below provincial average for income and education), behavioural determinants (residents had higher rates of smoking, sedentary activity and high fat diets) and lack of access to health care. The Health Forum developed a Health Improvement Plan to work on each of these determinants. Throughout its lifetime, the Health Forum proved to be both active and productive, leading to many cooperative ventures. This paper provides a brief overview of the approach taken with its Health Improvement Plan, as well as the successes and limitations of this approach. The experience of the Leeds, Grenville and Lanark Health Forum offers a practical model for public health units to work with partner agencies to address the determinants of health, as well as some insights into the requirements to sustain such a model.