Emergency service workers (ESWs) are at high risk of experiencing poor mental health, including posttraumatic stress disorder (PTSD). Programs led by ex-service organizations may play an unrecognized but critical role in mental health prevention and promotion. Behind the Seen (BTS) is an Australian ex-service organization that runs workshops to raise awareness and facilitate conversations around the mental health of ESWs. The purpose of the study is to conduct a qualitative evaluation of workshop participants’ experiences, to understand the acceptability and perceived usefulness over the immediate- (within 1 month), intermediate- (6 months) and longer-terms (12 months). Participants (n = 59 ESWs) were recruited using purposive sampling across five fire and rescue services in metropolitan, regional, and rural locations. Focus groups methodology was used for data collection and data were analyzed using iterative categorization techniques. Participants reported (i) a high perceived need for education about PTSD, (ii) highly salient aspects of the presentation that made for a positive learning experience, including the importance of the lived experiences of the facilitators in the learning process, (iii) key features of changes to intentions, attitudes, and behavior, and (iv) major aspects of the organizational context that affected the understanding and uptake of the program’s key messages. BTS was perceived as an acceptable means of delivering mental health, PTSD, and help-seeking information to ESWs. The program is a promising candidate for scaling-up and further translation.