In his late great paper, ‘Developmental psychiatry comes of age’, Bowlby (1988c) bemoaned the ‘kidnapping’ of the term ‘biological psychiatry’ by an exclusively biochemical and genetic approach to psychological ill health. Theories of psychological development, he argued, if based on sound ethological and evolutionary principles, are no less ‘biological’ than is research in neurotransmitter chemistry. Yet twenty-first century mental health research and practice is inescapably entwined with advances in neuroscience. The integration of psychodynamic ideas into psychiatry has always been bedevilled by the difficulty in translating the language of the inner world into the quantifiable terms of scientific psychiatry. As the quotation above implies, a key feature of Attachment Theory is its attempt to combine the psychological and subjective with the biological and the objective. Out of this encounter there is beginning to emerge the possibility of a more psychologically meaningful psychiatry, and a more scientifically based psychotherapy. Before considering that possibility in more detail a brief diversion into psychobiology is in order.