Preliminary results concerning difficulty levels of client cases in "Simulations in Developmental Disabilities: SIDD" are presented. Participants conducted assessments to identify causes of problem behavior and propose treatments for 10 clients. Although SIDD may teach clinical decision-making skills, providing numerous cases did not guarantee learning for all participants. Exposure to a difficult case early in instruction was associated with better overall performance by participants. Additionally, treatment performance best indicated perceived difficulty level. Further experimental research comparing order o f difficulty is recommended.