本研究指出，雙重層次之轉換型領導，會分別透過不同層次主管與部屬 交換關係對不同層次員工服務績效產生影響。為避免共同方法變異，本研究 取樣自台中地區一間大型商業銀行，共計回收計23 間分行，共組成有效的 228 組主管─成員對偶樣本資料。本研究發現，雙重層次之轉換型領導對於不 同層次員工服務績效均有顯著性之影響。其中，個人層次之轉換型領導透過 主管與部屬交換關係對員工服務績效產生影響。群體層次之轉換型領導透過 群體層次主管與部屬交換關係對群體層次員工服務績效產生影響。此外，本 研究亦指出，主管與部屬交換關係差異性對兩個層次主管與部屬交換關係以 及員工服務績效之間具有顯著負向干擾效果。本研究最後，亦提出理論與實 務上之管理意涵以及未來研究方向。

Conceptualizing superior customer service as behaviors exhibited by people who have direct interactions with customers in the workplace, we proposed a multilevel theoretical model that identified transformational leadership as the primary source, and the quality of leader-member exchange (LMX) as the underlying mechanism through which leadership exerts its positive influence on employee service performance, at both the individual and group levels. We also identified LMX differentiation within the group as a moderator between LMX quality and service performance. Data from 228 leader-member dyads of 23 branches in a large commercial bank revealed that both group-level transformational leadership and group LMX were meaningful group-level constructs that had significant positive effects on group service performance. More intriguingly, LMX differentiation played the role of a cross-level moderator that mitigated such relationship at the group level. The theoretical and practical implications of our findings are discussed in the service organizational context.