Purpose: This paper aims to explain the direct effect of supply chain integration on operational performance of manufacturing companies and the mediating effect of internal integration on the relationship between external integration and operational performance.Design/methodology/approach: From an organizational capabilities perspective we consider internal integration as a set of intra-organizational capabilities and customer integration and supplier integration as a set of inter-organizational capabilities. In the basis of a sample of 75 Moroccan manufacturing companies, we used PLS – Structural Equation Modeling to study the direct effect of customer integration, internal integration and supplier integration on operational performance of manufacturers and to analyze the mediating effect of internal integration. Findings: The results show that customer integration, internal integration and supplier integration are all positively and significantly related to operational performance of the manufacturer and internal integration mediates relationship between costumer integration and operational performance but not relationship between supplier integration and operational performance.     Research limitations/implications: This study focuses on a set of best practices for integrating flows and business processes that industrial companies need to implement in order to create value for final consumer and show how to use internal integration practices to benefit more from external integration.Originality/value: The result of this study extends the developing body of literature on supply chain integration by analyzing the effect of interaction between internal and external integration on the operational performance towards an organizational capabilities perspective in a specific Moroccan industrial context.

Supply chain integration has become a major challenge for companies in the current context. Information sharing, and collaboration improve supply chain flexibility, tractability, and efficiency. Several studies have demonstrated, the positive and the significant relationship between supply chain integration and firm performance. Other studies have focused on the factors that affect this relationship. Supply chain complexity is a contingency factor that affects this relationship. Based on the literature review and through a confrontational approach, the authors propose a conceptual model to show how the complexity of supply chain affects the benefit of integration. Propositions are posited with suggestions for further research. Authors suggest that there are three dimensions of supply chain complexity which moderate the effect of supply chain integration on the firm performance: upstream, internal and downstream complexity; that there is a taxonomy of firm's group based on their level of each dimension of complexity and the effect of integration differs from one group to another.