Studies of professional genres and professional practices are invariably seen as complementing each other, in that they not only influence each other but are often co-constructed in specific professional contexts. However, professional genres have often been analyzed in isolation, leaving the study of professional practice almost completely out, except as providing context for specific analyses, thus undermining the role of interdiscursivity in professional genres and practices. Drawing examples from a range of professional contexts, in particular from business and international arbitration practice, this paper argues for a shift towards an integration of discursive and professional practices, thus emphasizing the function of interdiscursivity in critical genre analysis.