<p>An immense corpus of work documents deleterious effects of loneliness on physical health, cognition, psychological symptoms, and wellbeing. In this Review, we argue that the widespread assumption that loneliness is unidimensional may lead to imprecise interpretations of findings and hamper intervention efforts. We critically revisit a longstanding multidimensional loneliness framework that posits two distinct dimensions: emotional loneliness (perceived lack of intimate connections) and social loneliness (perceived deficits in social networks). We demonstrate how distinguishing loneliness dimensions may provide a clearer picture of the nature of loneliness and its correlates, risk factors and consequences. For instance, emotional loneliness appears to be a more severe typology that overlaps greatly with pathology, whereas social loneliness is more reflective of deficits in social connectedness and social support. We additionally evaluate the utility of this multidimensional framework in the domains of clinical practice and public health and provide suggestions to stimulate further research.</p>