This study tests the hypothesis that the role identity of street-level bureaucrats is related to variation in their discretionary decisions in relation to the behavior of citizen-clients. The study draws on cross-sectional survey data on 465 officers from prisons in Denmark. Results from the study show a negative correlation between prison officers role identity as formalistic (state-agent) and the likelihood of differentiating in response to citizen-clients’ behavior. Correspondingly, the results shows a positive relationship between informal rule identification (citizen-agent) and differential responses against citizen-client behavior. The findings indicate a causal relationship between street-level bureaucrats’ role identity and their discretionary decisions.