Studying how the public behaves after a nuclear emergency will help to assess overall morbidity and mortality. Pre-event education might help to shape behaviour, but how best to engage people with emergency communications for low likelihood, high-impact events is unknown. We did a systematic review to identify factors that predict behaviour in preparation for a nuclear incident, factors that predict behaviour in the immediate aftermath of a nuclear incident, and preferences among members of the public for information designed to educate them about which actions to take in the event of a nuclear incident. In general preparedness, behaviour was predicted by factors including perceived coping effectiveness and having children, among others, but absence of preparedness was attributed to fatalistic attitudes. Importantly, for pre-incident communications to be accepted and recommendations adhered to, the source had to be trusted and perceived to be credible. However, it is notable that family needs, such as picking up children from school, were a stronger predictor of behaviour in a nuclear emergency than communicated directives from authorities. If pre-incident education about nuclear incidents is to be used, several factors—including the source and method of communication, the content, and format of messaging—might increase public engagement with messages and promote the uptake of protective behaviours in a radiation event.