Attachment theory and research have offered fundamental insights into early sociopersonality development for the past quarter-century. As its scope expands throughout the life course with applications to developmental psychopathology, however, attachment work faces important conceptual and methodological challenges. These include (a) expanding Bowlby's theoretical formulations to address developmental changes in the nature of attachment organization beyond infancy, the converging influence of multiple attachment relationships, and the nature and development of internal working models; (b) systematically validating assessments of attachment security for older ages in the context of enhanced theoretical understanding of how attachment itself changes with age; (c) new methodological approaches to understanding the relations between attachment and later behavior in light of empirical evidence of stability and change in attachment security and the need for explicit theoretical predictions of the sequelae of attachment security; and (d) more complex conceptualizations of the associations among attachment, contextual risk, and later behavior. These are similar to the challenges facing the original pioneers of attachment theory and research, suggesting that familiar problems must now be reconsidered against the landscape of new applications of attachment work and the insights of contemporary developmental science.