The history and development of attachment theory are reviewed. Research has focused on four major patterns of attachment in infancy: one pattern of secure attachment and three patterns of insecure attachment (avoidant, resistant, and disorganized). These patterns have been shown to reflect different histories of parent-child interaction and affected subsequent development up to age eight. More recently, methods have been developed for identifying similar patterns of attachment in preschoolers, five to seven year olds and adults. Future research is likely to focus on the development of attachment patterns and their transmission from one generation to another. New data on the relationship between attachment and behaviour problems has generated mutual respect and collaboration between clinicians and researchers.