The authors provide a context for this special section by arguing that the attachment relationships of infancy fulfil an evolutionary role in ensuring that the brain structures that come to subserve social cognition are appropriately organised and prepared to equip the individual for the collaborative existence with other people for which his or her brain was designed. Processes as fundamental as gene expression or changes in receptor densities can be seen as direct functions of the extent of understanding of mental states provided by the caregiving environment. If the attachment relationship is indeed a major organiser of brain development, it is even more important to understand the processes that underpin the transgenerational transmission of attachment patterns. The contributions of the papers in the special section to understanding the role of reflective function in the development of attachment and social cognition are reviewed, and the implications for the development of both theory and practice are explored.