Background. The paper is concerned with the use of epidemiological methods to measure the rates at which different strata of a defined population participate in community health promotion projects. The specific aim was to estimate the incidence rates of participation in projects sponsored by the Western Australian Health Promotion Foundation (Healthway), separately for sociodemographic and health-related behavioural subgroups.Methods. Data were drawn from Healthway sponsorship projects in 1992. Each sport, arts and racing project was associated with promotion of a health message and creation of a health promoting environment. The study used a two-stage sampling design. Thirteen of 57 large sponsorship projects and 30 of 129 small projects were selected. In the second stage, respondents were randomly surveyed from among project participants. A total of 4060 respondents aged greater than or equal to 10 years was sampled from the 43 selected projects. Population-based incident participations were estimated and were related to person-years at risk.Results. The total participation rate was 4.01 per person-year. The rate was very high at ages 10-14 years and thereafter declined with increasing age. Compared with the least socially disadvantaged 25% of population, the participation rate fell by around one-third in the medium and high disadvantage groups, but exceeded the baseline by a ratio of 1.85 (95% confidence interval : 1.57-2.18) in the most disadvantaged 10% of population. The effect was most pronounced at ages 10-19 years. Participation was higher in those who smoked, drank alcohol unsafely, reported sunburn and reported tow consumption of fruit and vegetables. However, participation was reduced in people who were sedentary.Conclusions. Epidemiological methods can be used to evaluate the distribution of participation of a population in community health promotion projects. The Western Australian Health Promotion Foundation has been successful in reaching disadvantaged youth.