Using voluntary blood donation as a case example, the study on which this article is based explored not only the extent, or breadth, of community involvement in social policy behaviours, but also the continuity, or depth, of this commitment. Demographic and motivational data were collected through a postal questionnaire returned by 1,784 persons who had voluntary donated blood at least once in metropolitan Toronto between 1974 and 1978. An empirical distinction was also drawn between the 'active' and the 'lapsed' donor. The study found that while certain sectors of society were probably disproportionately represented among those who close to undertake voluntary social behaviours, the continuity of these actions could not be statistically associated with demographic or socio-economic variables. However, it did find that donors initially motivated by 'external' considerations such as convenience of location were more likely to lapse, while those for whom moral considerations and a sense of community were most important were more likely to continue as active donors. The general conclusion suggests that manipulating the context may be useful to broaden the initial participatory base in voluntary actions, but to produce continuity in this involvement the challenge must be phrased in moral language.