People who are unable to make decisions about participating in research rely on proxies to make a decision based on their wishes and preferences. However, patients rarely discuss their preferences about research and proxies find it challenging to determine what their wishes would be. While the process of informed consent has traditionally been the focus of research to improve consent decisions, the more conceptually complex area of what constitutes ‘good’ proxy decision-making for research has remained unexplored. Interventions are needed to (...) improve and support proxy decision-making for research but are hampered by a lack of understanding about what constitutes decision quality in this context. A global increase in conditions associated with cognitive impairment such as dementia has led to an urgent need for more research into these conditions. The COVID-19 pandemic and subsequent necessity to conduct research with large numbers of critically ill patients has made this need even more pressing. Much of the empirical research centres on the desire to improve decision accuracy, despite growing evidence that authenticity is more reflective of the aim of proxy decisions and concerns about the methodological flaws in authenticity-focused studies. Such studies also fail to take account of the impact of decision-making on proxies, or the considerable body of research on improving the quality of healthcare decisions. This paper reports a concept synthesis of the literature that was conducted to develop the first conceptualisation of ‘good’ proxy decisions about research participation. Elements of decision quality were identified across three stages of decision-making: proxy preparedness for decision-making which includes knowledge and understanding, and values clarification and preference elicitation; the role of uncertainty, decisional conflict, satisfaction and regret in the decision-making process; and preference linked outcomes and their effect. This conceptualisation provides an essential first step towards the future development of interventions to enhance the quality of proxy decision-making and ensure proxy decisions represent patients’ values and preferences. (shrink)