This paper analyses three levels of interaction among firms: regional, domestic and international, the analysis relying on cross-functional supplier evaluations by their customers. The statistical analysis reveals that indeed three groups with different evaluation results can be distinguished. Contrary to expectations, though, regional suppliers were not better evaluated than domestic suppliers, while international suppliers scored weakest. Cross-functional differences in assessment were found, which urges researchers to collect cross-functional data for cluster assessment. We conclude that external linkages play an important role in understanding clusters and that the domestic level has to be taken into consideration of an analytical entity of its own.