Wales is a small country, with an ageing population, high levels of population health need and an economy with a significant reliance on public services. Its health system attracts little attention, with analyses tending to underplay the differences between the four countries of the UK. This paper helps redress this via a case study of Welsh mental health policy, services and nursing practice. Distinctively, successive devolved governments in Wales have emphasised public planning and provision. Wales also has primary legislation addressing sustainability and future generations, safe nurse staffing and rights of access to mental health services. However, in a context in which gaps always exist between national policy, local services and face-to-face care, evidence points to the existence of tension between Welsh policy aspirations and realities. Mental health nurses in Wales have produced a framework for action, which describes practice exemplars and looks forward to a secure future for the profession. With policy, however enlightened, lacking the singular potency to bring about intended change, nurses as the largest of the professional groups involved in mental health care have opportunities to make a difference in Wales through leadership, influence and collective action.