This paper proposes a method to quantify the contribution of inequalities of opportunities and inequalities due to differences in effort to be in good health to overall health inequality. It examines three alternative specifications of legitimate and illegitimate inequalities drawing on Roemer, Barry and Swift‟s considerations of circumstances and effort. The issue at stake is how to treat the correlation between circumstances and effort. Using a representative French health survey undertaken in 2006 and partly designed for this purpose, and the natural decomposition of the variance, the contribution of circumstances to inequalities in self-assessed health only differs of a few percentage points according to the approach. The same applies for the contribution of effort which represents at most 8%, while circumstances can account for up to 46%. The remaining part is due to the impact of age and sex.
