Behavioral economics builds on insights from behavioural sciences, primarily psychology, and aims to explain the behaviour of (groups of) individuals under conditions of scarcity. It applies an empirical methodology grounded in econometrics and based on experimental research. The authors' proposition is that behavioural law and economics rooted in experiments is a valuable approach to legal studies that complements pre-existing law and economics. Experiments maximise the opportunity to identify causal links and norms as building blocks of the law as interventions in human behaviour, and hence are well suited in the context of empirical legal studies. The research design menu includes variables such as hypothetical decisions versus actual behaviour, experiments with or without full randomisation, pure or quasi, lab versus field, and natural experiments versus experiments that can be manipulated.Behavioural economics operates under conditions of incentive compatibility and the no-deception principle. In this article, the authors set out a research agenda for behavioural law and economics research, covering private law (consumer and contract law as well as liability and tort law), administrative law, and economic law.