Ten years ago, Holm's highly influential paper "Goodbye to the simple solutions: the second phase of priority setting" was published [Holm S. Goodbye to the simple solutions: the second phase of priority setting in health care. British Medical Journal 1998;317:1000-7]. Whilst attending the 2nd International Conference on Priorities in Health Care in London, Holm argued that the search for a rational set of decision-making rules was no longer adequate. Instead, the priority setting process itself was now thought to be more complex. Ten years later, the Conference returns to the UK for the first time, and it is timely to describe some new tools intended to assist both researchers and decision-makers seeking to develop both rational and fair and legitimate priority setting processes. In this paper we argue that to do so, researchers and decision-makers need to adopt an interdisciplinary and collaborative approach to priority setting. We focus on program budgeting and marginal analysis (PBMA) and bring together three hitherto separate interdisciplinary strands of the PBMA literature. Our aim is to assist researchers and decision-makers seeking to effectively develop and implement PBMA in practice. Specifically, we focus on the use of multi-criteria decision analysis, participatory action research, and accountability for reasonableness, drawn from the disciplines of decision analysis, sociology, and ethics respectively.