Nostalgia, a sentimental longing for the past, is an ambivalent—albeit more positive than negative—emotion. Nostalgia is infused with sociality, as it refers to important figures from one’s past or to momentous life events that include those figures. Dispositional nostalgia is related to prejudice reduction via increases in a form of sociality, empathy. Experimentally induced nostalgia fosters sociality, operationalised as social connectedness (sense of acceptance). Social connectedness, in turn, has downstream consequences for (1) inspiration and goal-pursuit, (2) self-continuity and wellbeing, as well as (3) inclusion of an outgroup member in the self or outgroup trust and intergroup contact intentions. At the collective level, nostalgia confers sociality benefits to the ingroup (favourable attitudes, support, loyalty, collective action, barrier to collective guilt), but is also associated with negative sides of sociality such as outgroup rejection and exclusion. Collective nostalgia’s sociality is amenable to exploitation and can have controversial ramifications.<br/><br/>