It has been argued theoretically and empirically that the analysis of business processes requires the decomposition of an integrated system. However, in order to innovate a business process, cognitive integration activities that try to understand the decomposed features of the business process as an integrated system are essential. This research aims at 1) empirically investigating the cognitive process of integrating multiple diagrams while using object-oriented methodologies in process modeling ; 2) identifying a cognitive integration strategy that supports the successful comprehension of business processes with the use of multiple diagrams ; and 3) proposing guidelines for developing supporting tools for effective business process engineering by using object-oriented process modeling.