Responses to separation and reunion are known to differ across cultures, and also across various types of psychopathology. However, few studies have focused on examination of cross-cultural validity of different attachment processes in relation to early emotional problems. Here, security of attachment, assessed through examination of responses to separation from and reunion with the mother, is examined in American and Japanese four-year-olds who vary in degree of internalizing problems. American and Japanese children did not differ on security, except when gender is considered. Japanese girls show particularly high levels of insecurity. The same behavior patterns defined as problematic in one cultural context (e.g. in American children as immature, dependent behaviors), but acceptable and valued in another cultural context (e.g. in Japanese children as Amae behavior), correspondingly relate differently to early emotional problems in Japanese and American children. Such differences suggest that the concept of security may have to be re-examined from different cross-cultural and psychopathology perspectives before making claims to universal validity.