Emergency services are under enormous pressure to offer programmes that could protect their staff from the psychological impact of stressors encountered in their roles. There has been a surge in the number of pre-incident training programmes aimed at first responders to maintain their psychological wellbeing after critical incidents. These include pre-employment screening programmes, psychoeducation, operational training, line manager training and interventions aimed at improving resilience, wellbeing or stress management. Whilst developed with the best intentions, these programmes vary in efficacy. Therefore, knowing what training to offer first responders prior to exposure to critical incidents is far from clear. In this review, we critique the available evidence and make recommendations about what to offer and what to avoid offering first responders prior to exposure to critical incidents. We found no evidence of the effectiveness of pre-employment screening or psychoeducation offered as a standalone package, and little evidence for interventions aimed to improve wellbeing and Dr Jennifer Wild is a consultant clinical psychologist, associate professor and NIHR Oxford BRC Senior Research Fellow at the University of Oxford. Her area of expertise is in developing and evaluating evidence-based interventions to prevent stress-related psychopathology in emergency responders. Professor Neil Greenberg is an academic psychiatrist, who is a specialist in the understanding and management of psychological trauma, occupational mental ill-health and post traumatic stress disorder.