Theoretically, the more important a role-identity is to a person, the more it should provide a sense of purpose and meaning in life. Believing one's life to be purposeful and meaningful should yield greater mental and physical well-being. These hypotheses are tested with respect to the volunteer role, specifically, Mended Hearts visitor, in which former heart patients visit current heart patients and their families in the hospital. Analyses of survey data from Mended Hearts visitors (N = 458) confirm that a sense of meaningful, purposeful life mediates the positive influences of role-identity salience on mental and physical health. The results hint at an unfolding process: the more time spent in volunteer activities, the more important the volunteer identity. The greater the identity importance, the more one perceives one matters to other people, which in turn enhances purpose and meaning. The more life seems purposeful and meaningful, the better one's well-being. (Contains 5 tables and 5 footnotes.)