Does self-esteem instability explain the link between academic contingent self-worth and mental health threats? Dimensionality matters

<b>Objectives:</b> Theory suggests that students who base their self-worth on academic successes and setbacks risk poor mental health because their self-esteem is unstable. This hypothesis should be revisited given recent evidence that academic contingent self-worth (ACSW) is multidimensional, with some dimensions related to threats to mental health and other dimensions unrelated or inversely related to said threats. <b>Participants and methods:</b> Therefore, the present research examined, in an undergraduate sample (<i>N</i> = 273), whether self-esteem instability mediated the link between different ACSW dimensions and stress and three types of well-being (psychological, emotional, and social). <b>Results:</b> Supporting predictions, at two time points, self-esteem instability mediated the link between the general-contingency dimension and heightened stress and diminishment of the three types of well-being; conversely, the positive-contingency dimension related to lower stress and higher psychological and emotional well-being. <b>Conclusions:</b> We discuss possible reasons different ACSW dimensions differentially relate to mental health threats and suggest ways to reduce the vulnerability of students high in general ACSW.