Posttraumatic Stress Disorder (PTSD) following a traumatic injury is a significant public health concern impacting approximately a third of traumatically injured patients. In 2018, the American College of Surgeons (ACS) Committee on Trauma recommended implementation of PTSD screening and brief intervention in level 1 trauma centers to meet the mental health needs of this underserved population. In March 2022, ACS revised its standards to include a requirement for mental health screening and referral process in level 1 and level 2 trauma centers. However, implementation of these programs has been limited. One barrier to implementation has been the lack of cross-trained trauma and health psychologists to support the development and implementation of trauma-focused programs in acute and critical care settings. This paper is a call to action to bring together experts in the fields of trauma and health psychology to effectively address training gaps in post-injury PTSD and medical traumatic stress. Through development of trauma and health psychology cross-training models, the field of psychology can collaborate to meet the increasing demand for trauma-focused psychologists in acute and critical care settings.