PurposeThis study investigated the effects of social capital on frontline bank employee's adaptive selling behavior via the psychological process. Frontline bank employees' positive social relationships enhance their perception of the work environment and encourage work engagement. With the multiple mediation model, both internal and external social capital have direct and indirect influence on the frontline bank employee's adaptive selling behavior.Design/methodology/approachData for this study were collected from a cross-sectional sample of retail banking industry in Korea. Specifically, using two-step procedures, employees of financial service or insurance sales department in banks were selected and online survey questionnaires were distributed to them. Data from 330 employees were collected and analyzed.FindingsThe results of this study showed how social capital affects frontline bank employees' person–job fit as a cognitive psychological process, leading to work engagement as an emotional psychological process and, in turn, more adaptive selling behavior. Using multiple mediation analysis, the results showed that work engagement on its own exerts a mediating effect on social capital, whereas a person–job fit does not.Research limitations/implicationsThis study applied both aspects of the social capital concept by dividing it into internal and external social capital, and exploring each separately. This study examined the influence on psychological processes and behavioral response by distinguishing between the two forms of social capital. Second, this study expands the previous studies by introducing social capital as an antecedent factor of frontline bank employees' adaptive selling behavior. Finally, this study explains how frontline bank employees' relational resources (i.e. social capital) influence their emotional aspect (i.e. work engagement) and cognitive aspect (i.e. person–job fit), which ultimately influence performance-driven behavior (i.e. adaptive selling behavior).Practical implicationsThis research showed the importance of hiring frontline bank employees with excellent social capital capabilities. Furthermore, this study underscored the fact that organizations require preparing and providing practical management methods that can improve the social capital of their current frontline employees. Last, organization need to design the job in a way that innately improves frontline employees' social capital. Therefore, these jobs provide many opportunities for frontline bank employees to use their ability to build relationships in their interactions with customers and make practical decisions to achieve job performance.Originality/valueThis study improved our understanding regarding the importance of employees' social capital by revealing the psychological process of how frontline bank employees' social capital affects adaptive selling behavior. Second, this study expands on the literature by introducing internal and external social capital as an antecedent factor affecting the adaptive selling behavior of frontline bank employees. Furthermore, this study advances understanding on the manner in which relational resources of frontline bank employees (i.e. social capital) influence the emotional (i.e. work engagement) as well as the cognitive aspects (i.e. person–job fit), which ultimately influence performance-driven behavior (i.e. adaptive selling behavior).