Debriefing occurs after an experiment at which time researchers provide participants with the experiment’s full rationale, answer participants’ questions, inquire about their experience, disclose if deception was used, and alleviate any distress caused by participation. This process evolved over time as a way to protect research participants from harm while participating in psychological research, especially research that used deception. The practice of debriefing is considered mandatory by most regulated research ethics boards (REBs) or institutional review boards (IRBs) and governing psychological bodies (e.g., the Canadian Psychological Association and the American Psychological Association). This entry introduces research participation and debriefing as it relates to psychology, including a brief historical review of the inclusion of ethical guidelines, specific requirements for research, and debriefing in practice.