Purpose: The purpose of this study was to determine the roles of employee proficiency, adaptivity and proactivity in predicting different aspects of internal service. Design/methodology/approach: Managers evaluated 142 professional employees on proficiency, adaptivity and proactivity and about six weeks later 2–3 internal customers evaluated each of the employees on dimensions of internal service, namely reliability (i.e. performing dependably and accurately), assurance (i.e. knowledge, courtesy, and the ability to inspire trust and confidence), responsiveness (i.e. willingness to help customers and provide prompt service) and empathy (i.e. caring and providing individualized attention). Findings: Employee proficiency and proactivity were the main predictors of delivering reliable services. Employee proficiency was the main predictor for creating a sense of assurance. Employee adaptivity was the main predictor of being viewed as responsive. Employee proactivity was the main predictor for establishing a sense of empathy. Practical implications: In a given situation, some aspects of internal service will be more important than others. The results will enable organizations to improve internal service in a more effective and efficient manner by developing interventions that are targeted at the specific dimension of interest. Originality/value: The authors identified the types of employee behaviors that are likely to be most effective in impacting different aspects of internal service.