His research concentrates on political behavior and public policy. Professor Mullinix examines the extent to which political parties and elected officials shape the public’s attitudes toward various policies. More recently, his research has focused on the effects of wrongful convictions for attitudes toward the death penalty and the effects of racial disparities in the justice system for trust in police. ​He has a related research agenda on the generalizability of experiments in the social sciences. Professor Mullinix has published his research in Political Behavior, Political Communication, International Journal of Public Opinion Research, Political Research Quarterly, Journal of Experimental Political Science, Presidential Studies Quarterly, PS: Political Science & Politics, and the Policy Studies Journal.