In this paper, we examine the implications for understanding the practices of researching business networks that result from the ontological paradigm choices that researchers make. This is not an esoteric theoretical problem; without understanding these choices and their implications for research practice, much of our knowledge of many business-to-business marketing problems may suffer from superficiality and rely on overly descriptive accounts and narratives. Based on three common building blocks in understanding social systems (individuals, social practices and processes, and social structures), we examine the implications of adopting two different research traditions, namely: critical realism and constructivism. Drawing on data from an in-depth investigation of a construction project undertaken in the UK, we apply these research traditions to a managerial phenomenon, specifically the practice of novation in temporary organisational networks. In so doing we examine what we may realistically learn from each approach and ask what are the implications for the practice of research.