The original Ainsworth model posited that there are three persistent patterns of attachment—secure-attached, insecure-avoidant, and insecure-resistant—and that these could be identified by the Strange Situation procedure, wherein an infant, over seven 3-minute episodes, is variously separated and reunited with the mother and a stranger. The degree to which these modes persist, whether the "insecure" modes may convey a selective advantage in some settings, how much they predict about later life, and what they say about such phenomena as attachment to inanimate objects or locations have been matters of controversy, which this volume does not address in much detail. It does include a very brief introduction to the work of Bowlby, which may not be accessible to the reader entirely new to this area. In general, this volume presupposes both some familiarity with and acceptance of this model. Given its persistent utility, this is a fair demand—no other model has yet risen to match it, either in heuristic value or as a stimulus for research.