In formulating attachment theory, Bowlby made a number of important conceptual contributions to our understanding of human development. Discussed here are the balance (rather than the conflict) between attachment and exploration, the concept of internal working models; and the parent as a psychological secure base. In addition, Bowlby's "theory of reality" is examined, integration of Bowlby's and Erikson's ideas regarding attachment and culture is suggested, and Bowlby's open-minded approach to theory construction is acknowledged.