This special issue of the Infant Mental Health Journal presents the plenary addresses from WAIMH's 7th World Congress in Montreal, Canada (2000). As we noted in the program booklet for that congress, the field of infant mental health coalesces around three common assumptions: infant behavior cannot be viewed separately from relationships with others; infants' most important relationships are with their primary caregivers; and infant caregivers have relationships with others in their social contexts. These assumptions rest on such historical reminders that infants are born into a social world , which consists of reciprocal relationships ), (especially) with primary caregivers , who may or may not have unresolved issues that construct barriers to the development of secure social-emotional relationships . All of these characterizations provide a basis for understanding that infant mental health is grounded in the reciprocal interactions that infants have with others within the extraordinarily diverse contexts in which infants live and negotiate the world. Infants, caregivers, extended family members, and the broader social and cultural networks in which these families are embedded, provide the contexts that influence social and emotional development and generate issues relevant to infant mental health .
If there is any common theme cutting across all of the contexts within which human infants live and thrive or atrophy and die, it is diversity. The theme of the 7th World Congress, "Diversity: Challenges and Opportunities in Infancy," captured the Program Committee's desire to examine contemporary knowledge about the infant in multiple contexts. The congress subthemes were selected to reflect trends in research, clinical practice, and social policy, or to draw attention to issues that should enter into the domain of topics that define modern "trends." The subthemes and plenary speakers whose works are published in this issue of the Infant Mental Health Journal were "Brain -Behavior Interface" (Megan Gunnar, United States), "De-