This paper concerns the ontology and epistemology of comparative research, which are the foundations of a research strategy. It builds upon a Realist ontology (Bhaskar, 1975, 1979; Sayer, 1984,1985, 2000; Lawson, 1997, 1999) of necessary and contingent relations forming causal mechanisms, in order to extend existing frameworks for explaining difference and change in housing networks. Housing ne...