The present study employed a longitudinal design to test a moderated-mediation model of attempted change among disordered gamblers. Specifically, self-discontinuity (i.e., feeling that gambling has fundamentally changed the self) was expected to lead to attempted change through feelings of nostalgia for the pre-addicted self. Moreover, this indirect relationship was hypothesized to be conditional upon gamblers’ implicit theories of behaviour (i.e., malleable versus stable). To this end, a community sample of disordered gamblers (N = 243) completed measures of self-discontinuity, nostalgia, implicit theories, and readiness to change. Three months later, participants were asked whether they had made an attempt to change their gambling behaviour since the initial session. As expected, self-discontinuity lead to attempted change through nostalgia, but only for gamblers who believed that behaviour was malleable, as opposed to stable. As few disordered gamblers attempt to change their behaviour, these findings are important in promoting positive behavioural change.