Professor MacDonald works on a variety of topics in criminology including the study of crime and violence; race and ethnic disparities in criminal justice; and the effect of public policy responses on crime. In 2012 he was awarded the David N. Kershaw Prize from the Association for Public Policy Analysis and Management for contributions to Public Policy by Age 40. In 2017 he was elected Fellow of the Academy of Experimental Criminology. His research has been published in leading scientific journals across different disciplines including the Proceedings of the National Academy of Sciences, American Journal of Epidemiology, American Journal of Public Health, Criminology, the Economic Journal, Journal of American Statistical Association, and the Journal of Royal Statistical Society. His research has been funded by National Institutes of Health (NIH), the Centers for Disease Control and Prevention (CDC), and National Institute of Justice (NIJ).
A current focus of his work is on examining how policies and programs to change the land use of places can reduce crime and violence in neighborhoods. His current CDC and NIH funded research involves a randomized community trial of the effect of vacant lot remediation and stabilization on violence and injury outcomes and a randomized trial of abandoned housing remediation on substance abuse and violence. He is also active in studying racial disparities in criminal justice processing, and ways to reduce these disparities through policy and program reforms.