Modern emotion theories emphasise the adaptive value of emotions. Emotions are by no means always helpful, however. They often must be regulated. The study of emotion regulation has its origins in the psychoanalytic and stress and coping traditions. Recently, increased interest in emotion regulation has led to crucial boundary ambiguities that now threaten progress in this domain. It is argued that distinctions need to be made between (1) regulation of emotion and regulation by emotion; (2) emotion regulation in self and (...) emotion regulation in others; and (3) conscious and nonconscious emotion regulation. Using a process model of emotion generation, this review considers promising research on basic processes and individual differences in emotion regulation and poses five theoretical challenges. (shrink)