Studies have shown that a client’s characteristics can affect frontline professionals’ decision-making and use of discretion. However, we do not know whether these dynamics also exist in frontline professionals’ prosocial rule-breaking (PSRB): breaking rules to benefit clients. This study focuses on to what extent and how client characteristics affect PSRB by frontline professionals. Using an innovative within-person vignette experiment among professionals in social welfare teams in the Netherlands (N=58 professionals; 424 observations), we focus on clients’ earned, needed, and resource deservingness. The results show that all three elements of deservingness positively affect the willingness of professionals to engage in PSRB, but needed deservingness has the greatest effect. Through three focus groups (N=21 respondents), we build on this finding to reveal how different motives for PSRB align with various dimensions of deservingness. The results contribute to theory development on the use of discretion among frontline professionals.