Professor Langbein teaches quantitative methods, program evaluation, policy analysis, and public choice. Her research fields include: theories of bureaucratic discretion, productivity, principal-agent models, social capital, and cooperation in the workplace; theories of influence of interest groups in Congress and the bureaucracy; empirical applications in various policy areas, including the environment, education, defense, housing, criminal justice (death penalty and police), and corruption. Her articles have appeared in numerous journals on politics, economics, policy analysis and public administration. Her most recent publications examine the consequences of varying levels of discretion and employee voice in federal agencies. Her current research focuses on corruption. One recent paper examines the stability of corruption within countries. Another considers how the use of difference in difference designs, rather than commonly used national cross-section designs, raises questions about the efficacy of laws creating a merit-based professional bureaucracy to reduce street level bribe-requests.