More diversity in studies is needed to improve the generalizability of research on the ACE program. Issues concerning external validity and contamination of intervention groups also limit the current data. To increase diversity in ACE research, studies need to be conducted outside of Ohio and on different populations of patients. Rigorous studies should be conducted, especially prospective case-control studies with large sample sizes. This will increase the generalizability of ACE studies and create a stronger case for their effectiveness and implementation.