The present research examined whether social media websites increase feelings of nostalgia, and whether this nostalgic reverie promotes psychological and social health. Specifically, in comparison to control conditions, participants exposed to the websites Dear Old Love and Dear Photograph reported greater feelings of nostalgia (Studies 1–3), positive affect (Studies 1 and 3), life satisfaction (Study 1), and relationship need satisfaction (Study 2). Further, mediational analyses revealed that increased thoughts of nostalgia heightened subjective well‐being and social connectedness. Study 3 showed that the relationship between nostalgia and positive affect was specific to the Dear Photograph website and did not generalize to any website focused on close relationships. The implications of this research for nostalgia, internet use, and well‐being are further discussed.