It is increasingly argued that preferences and values for complex goods such as ecosystem services are not pre-formed but need to be generated through a process of deliberation and learning. While the number of studies incorporating deliberation in monetary and non-monetary valuation of ecosystem services is increasing, there is a limited theoretical basis to how values are influenced and shaped in social valuation processes. In this paper we present the Deliberative Value Formation (DVF) model, a new theoretical model for deliberative valuation informed by social-psychological theory. Anchored within a broader theoretical framework around shared and plural values, the DVF model identifies a range of potential positive (e.g. learning) and negative (e.g. social desirability bias) outcomes of deliberation and key factors that influence outcomes (e.g. ability to deliberate, institutional factors, power dynamics). It also conceptualises how values may be formed by ‘translating’ transcendental values, our principles and life goals, into more specific contextual values. Underpinned by this theoretical model, we present a six-step template for designing deliberative valuation processes. The DVF provides a theoretical and methodological framework for more rigorous monetary and non-monetary deliberative valuation, and enables more effective integration of social learning and plural knowledges and values in valuation and decision-making.