This study analyzes the relationship between the three main enterprise systems (Enterprise Resource Planning (ERP), Supply Chain Management (SCM), Customer Relationship Management (CRM)) and labor productivity. It reveals the performance gains due to different combinations of these systems. It also tests for complementarity among the enterprise systems with respect to their interacting nature. Using German firm-level data the results show that the highest productivity gains due to enterprise system usage are realized through use of the three main enterprise systems together. In addition, SCM and CRM function as complements, especially if ERP is also in use.