The study examines the effect of psychosocial safety climate (PSC) and psychological capital (PsyCap) on customer engagement through discretionary service behaviors including adaptive and proactive service behaviors (ASB and PSB). A field study of 56 managers, 513 service employees, and 560 customers in 56 branches of insurance companies was carried out to test a theoretical model using hierarchical linear modeling (HLM7). The results demonstrated that PsyCap and PSC were both positively associated with ASB and PSB at the individual level. The results also showed that an interaction between PsyCap and PSC was related to ASB but not PSB. This suggested that PsyCap and PSC interact in a synergic manner to affect service employees’ engagement in ASB, beyond their direct effects. At the branch level, ASB was not associated with customer engagement behavior, but PSB was. Furthermore, PSB mediated the relationship between PSC and customer engagement behavior, although ASB did not.