Income inequality is on the rise across the globe — an increasingly small portion of individuals control an increasingly large portion of wealth. Importantly, this inequality is associated with lower levels of happiness for citizens. In this paper, we review evidence regarding the psychological nature of this relationship. We examine central mechanisms that explain the link between income inequality and subjective well-being, including anxiety from status competition, mistrust, and hopes and fears about the future. We stress that perceptions of inequality matter as much as objective measures for well-being. Finally, we suggest some potential areas for future research regarding inequality and happiness and advise that this body of work be considered when developing and evaluating relevant policies.