Only a handful of studies have adopted a street-level bureaucracy (SLB) framework to study officer-offender interactions in probation services. Besides the clues provided by criminology research, there is little empirical evidence about how POs use their discretion and how the multiple constraints they encounter at work affect their delivery of services to probationers. Furthermore, little is known about how POs rely on their perceptions of offenders’ trustworthiness to make decisions. While it is generally agreed that frontline workers rely on their assessments of citizens’ key characteristics, few studies have specifically examined this issue taking stock of the notions of trust and trustworthiness. Yet, uncertainties persist regarding the role and effect of individual and organizational factors in the assessment of citizens’ trustworthiness. This research fills these gaps using an analytical framework that combines the conceptual insights from the SLB and trust research to explore the nature and conditions of officer-offender interactions. Two empirical studies were conducted in the public agencies responsible for probation in Belgium. First, I examined how POs adapt the delivery of services to probationers in response to pressure and work constraints. Hypotheses were examined with a thematic analysis of 29 semi-structured interviews conducted with POs and several first-line managers. Second, building on the theoretical and conceptual insights of trust, I examined how individual and organizational factors affect the importance officers attach to their trustworthiness assessments when choosing a given course of action with offenders. Hypotheses were tested with the structural equation modelling of survey data from a sample of 370 POs. The findings provide strong indications about how POs take into consideration the characteristics of their supervisees and how this information affects frontline work. In particular, the combination of the results of both studies shows that POs’ assessment of offenders is ...