Mental health problems are among the most common disabling health conditions in children and adolescents, and there is growing recognition worldwide of the critical role schools, and classroom teachers play in their prevention. For effective prevention and/or intervention, professional development for schools and teachers is crucial; however, this is currently lacking. Indeed, there is considerable variance between what government and state policies require of schools in terms of training at pre-service and currently employed teacher levels. Consequently, teachers generally lack the knowledge, skills, and confidence to meet the ever-increasing demands and expectations of children's mental health. This is even more apparent with reference to whole-school Universal Social Emotional Learning models and interventions. The findings from this current critical literature review highlight the disconnect between government expectations, teacher preparation and their (i.e., teacher's) capacity to identify and support child mental health problems in primary school classrooms. Given the critical role classroom teachers and schools (as a system) play in child mental health, it is crucial that training be provided for preservice teachers and currently employed practitioners.