Deliberative processes are a well-established part of health technology assessment (HTA) programs in a number of high- and middle-income countries, and serve to combine complex sets of evidence, perspectives, and values to support open, transparent, and accountable decision making. Nevertheless, there is little documentation and research to inform the development of effective and efficient deliberative processes, and to evaluate their quality. This article summarizes the 2020 HTAi Global Policy Forum (GPF) discussion on deliberative processes in HTA. Through a combination of small and large group discussion and successive rounds of polling, the GPF members reached strong agreement on three core principles for deliberative processes in HTA: transparency, inclusivity, and impartiality. In addition, discussions revealed other important principles, such as respect, reviewability, consistency, and reasonableness, that may supplement the core set. A number of associated supporting actions for each of the principles are also described in order to make each principle realizable in a given HTA setting. The relative importance of the principles and actions are context-sensitive and must be considered in light of the political, legislative, and operational factors that may influence the functioning of any particular HTA environment within which the deliberative process is situated. The paper ends with suggested concrete next steps that HTA agencies, researchers, and stakeholders might take to move the field forward. The proposed principles and actions, and the next steps, provide a springboard for further research and better documentation of important aspects of deliberation that have historically been infrequently studied.