Purpose The purpose of this paper is to investigate a special type of unethical behaviors among frontline service employees – unethical pro-organizational behaviors (UPB). Building on social identity theory, the paper examines how social identifications with the organization and customers interactively affect employees' engagement in UPB. The paper also explores the underlying psychological mechanisms that explain this effect.

Design/methodology/approach This study uses a multistage, sequential research design to test the hypothesized model. Studies 1A and 1B use scenario-based experiments with a randomized between-subjects design. Study 2 uses a survey design to replicate and expand the findings from Study 1 by collecting survey data from frontline service employees in various service sectors.

Findings The results across two studies reveal that high organizational identification will motivate employees to engage in UPB when the opportunity arises, while employees who also identify with customers will more likely abstain from committing UPB. Findings from the survey study also show that this interactive effect on UPB is achieved by devaluing customers as tools or placing fault upon them.

Originality/value This research provides a deeper exploration of the UPB at the organizational frontline. From a social identity theoretical perspective, this research examines how identification with customers and with the organization jointly shape frontline employees' engagement in UPB. In doing so, this research provides insight into the contextual limitations of existing UPB research while also offering practically relevant implications for managing UPB in frontline service contexts.