John Bowlby believed that humans, like other species, were predisposed toward relational experiences that satisfied an instinctual need for security (Bowlby, 1980, 1982, 1988).

• By providing sensitive and consistently reliable care, parents foster a sense of security in the child, which in turn promotes exploration, curiosity, adaptive regulation of emotion, and the development of positive mental representations of others as available and of the self as worthy of care.
• Conversely, insensitive and/or inconsistent care engenders anxiety and distrust. Of even more serious consequence, prolonged or permanent separation or abusive treatment from an attachment figure can seriously injure and fragment the individual's sense of self.

A central tenet of attachment theory is that the way attachment behavior becomes organized as a strategy for relating to others is carried forward and profoundly influences subsequent close relationships (e.g., parent-child, romantic, clinical alliance), personality and mental health (Bowlby, 1980).
For those of you unfamiliar with attachment theory, I highly recommend:

• Robert Karen's (1998) Becoming Attached, which provides a historical introduction to attachment theory and is both easy and entertaining to read. He also wrote an article by the same name (1990), which is a good brief overview.
• Those of you familiar with the theory, but wishing for more in-depth coverage of specific areas in the field, I refer you to Cassidy and Shaver's (1999) Handbook of Attachment.
• Click on links for a list of additional research labs working with attachment theory.