Over the past 20 years, cash transfers have become increasingly widespread within international development and global social policy. Often, their roll out is preceded by a trial or pilot phase aiming to check feasibility and effectiveness. These pilots can involve thousands of people. However, there is limited discussion within the literature (and even less in practice) of how and whether cash transfer trials and the research that they involve can respect ethical standards. This paper represents an initial step towards filling that gap. It does so by reviewing the latest literature pertaining to the ethics of cash transfers and social experimentation. It concludes by advancing a series of proposals that could support cash transfer trials to take place with greater respect for research ethics norms and in the best interests of participants. The paper’s findings have relevance for policymakers and development practitioners working with cash transfers and also for the smaller cognate world of Unconditional Basic Income (UBI) piloting.