As supply chains continue to replace individual firms as the economic engine for creating value during the twenty-first century, understanding the relationship between supply-chain management practices and supply chain performance becomes increasingly important. The Supply-Chain Operations Reference (SCOR) model developed by the Supply Chain Council provides a framework for characterizing supply-chain management practices and processes that result in best-in-class performance. However, which of these practices have the most influence on supply chain performance? This exploratory study investigates the relationship between supply-chain management planning practices and supply chain performance based on the four decision areas prodded in SCOR Model Version 4.0 (PLAN, SOURCE, MAKE, DELIVER) and nine key supply-chain management planning practices derived from supply-chain management experts and practitioners. The results show that planning processes are important in ad SCOR supply chain planning decision areas. Collaboration was found to be most important in the Plan, Source and Make planning decision areas, while teaming was most important in supporting the Plan and Source planning decision areas. Process measures, process credibility, process integration, and information technology were found to be most critical in supporting the Deliver planning decision area. Using these results, the study discusses the implications of the findings and suggests several avenues for future research.