Despite several suggestions that peer support is empowering for persons with mental health problems because of its mutual nature, few studies have empirically studied the role of its reciprocity and the effects on subjective well-being of clients from mainstream mental health care settings. Using data of 628 users of vocational and psychiatric rehabilitation centers (N = 51) in Flanders, the effects of the reciprocity of peer support on self-esteem and self-efficacy are explored by testing hypotheses derived from the theories of exchange, social capital, equity, and self-esteem enhancement. Results show that providing peer support is more beneficial than receiving it. One conclusion is that the net beneficial effects of receiving support from peers are overestimated.