Cardiovascular diseases are Canada's primary cause of death and hospitalisation, and are the second major cause of restricted physical activity. Quebec province, with a mortality rate of 399/100,000, has figures even higher than the national average of 323/100,000, and 7 out of every 10 Quebecois present at least one of the major cardio-vascular risk factors. Following an exploratory task force on this question, the Canadian government initiated a partnership programme with the provinces wherein the federal government and provincial governments would each contribute one million Canadian dollars over a five year period for heart disease prevention programmes. Quebec province selected three different projects in which multifactorial, multisectorial community-based programmes were to be implemented. The sites chosen for the projects were: a rural region situated on the banks of the St. Laurence River, a Montreal suburban district, and a multi-ethnic, socio-economic disadvantaged community in downtown Montreal. Despite a common public health approach and the ultimate goal of improving heart health through the lowering of risk factors, each project had its own specific major intervention strategy and primary target population. The projects were linked by a study design to evaluate community and family mechanisms which favour the adoption of low risk behaviours. A coordinating committee was formed to supervise the overall project which included strategic planning, consultancy services to project staff, methodology, development and implementation, and evaluation. Each specific project team was free, however, to choose its particular orientations.(ABSTRACT TRUNCATED AT 250 WORDS)