Introduction -- Developmental Realms -- The capacity for regret in children and adolescents -- Regret, resolution, and reparation in marital relationships -- The trajectory of remorse to regret in old age -- Cultural Realms -- The poetics of regret in repetition, mourning, and reparation -- Of regret and Plato's ghost -- Regret on the screen and regret as a screen -- Clinical Realms -- Regret, nostalgia, and masochism -- Development perspectives in the treatment of regret -- Clinical transformation of intolerable regret into tolerable regret -- Longing for a second chance.