Human excellences and defects - the virtues and vices of character - have been central to moral philosophy for fifty years. But though the developmental dimension of virtue ethics is mentioned even by Aristotle - as he says, 'it is a matter of no little importance what sort of habits we form from the earliest age' - it remains underexplored to this day. This is a significant theoretical gap in its own right. Filling it promises to yield new understanding not only of the processes by which vice and virtue are formed, but also of what vice and virtue are, and thus to address afresh the fundamental issue in virtue ethics: the relationship of vice and virtue to the proper development of human nature. However, this theoretical gap is one which also threatens to have practical consequences. Vice and virtue have been a prominent theme in recent public policy discussions, with character education envisaged as a key means by which early years interventions can address social problems. But if we do not understand how virtues and vices of character are formed, we cannot intervene effectively to promote or prevent their formation. And if we do not understand how the traditional vices and virtues relate to those developmental goals which lie more obviously within the reach of early years interventions - like warm relations with caregivers, the ability to focus on a task, or the ability to defer gratification - we have no way of evaluating whether these interventions really are promoting virtue, or if so, how. The proposed interdisciplinary research network aims both to address the theoretical gap identified above, and to devise theoretical tools with which to assess character-building interventions in the early years. It will do so by bringing moral philosophers working in virtue ethics together with experts in attachment theory, one of today's leading approaches in developmental psychology, which has been influential in public policy discussion on character but has yet to gain proper recognition from philosophers. It is able to take on both tasks because the network's theoretical and policy-focused ambitions stitch together neatly. According to attachment theory, attachment dispositions are the product of natural selection: clinging, following and so on evoke caregiving behaviour in adults, which favours survival. And individual attachment dispositions (secure or insecure) explain high-level psychological differences - e.g., in respect of the ability to co-operate or to regulate emotion. But are co-operativeness and emotion-regulation virtues - distinctively modern ones which deserve a place in philosophy alongside the Aristotelian and (post)-Christian catalogue? Or are they more basic dispositions which can underlie vice and virtue alike? Co-operativeness is socially useful, so if - as Philippa Foot maintained - the virtues are the traits necessary for us to lead our characteristic species life, the answer seems to be yes. But co-operation is as necessary for war and interest-rate fraud as it is for socially useful activity. The answer is thus decisive for the fundamental claim of neo-Aristotelian virtue ethics - that virtues and vices are natural excellences and defects. To evaluate that claim is the network's central theoretical goal. But co-operativeness and emotion-regulation are also typical goals of early years interventions: because of these traits' well-established links to secure attachment, if we can promote secure attachment (e.g. by teaching parenting skills), we know we can promote those traits. But are we thereby promoting virtue? If these traits are virtues, yes; if not, then either we are not promoting virtue, or we are doing so but do not yet properly understand why. Mapping the relationships between the traditional virtues and the high-level psychological traits attachment theory is in a position to explain is thus a path to fulfilling both the network's theoretical and its practical ambitions.