Canada is an “under-institutionalized” federation (Cameron and Simeon, 2002b). In the extensive world of intergovernmental relations (IGR) which exist between the federal, provincial and territorial governments, formal relations are said to be “the tip of the iceberg” (Kernaghan, 1985: 156). This leaves a good deal of governmental activity in Canada within the realm of ‘informal relations,’ a world of intergovernmental relations between public servants without formal rules to guide the process. Broadly considered, those relations are important (Inwood et al., 2011). However, scholarship is not neutral on this point: informal relations are frequently treated as being unstructured and inefficient (Meekison et al., 2004). This dissertation tackles the issue of informal relations by asking, at the level of public servants, what are the effects of informal relations on intergovernmental relations? If they are ‘important,’ what is the nature of this importance? Using a model derived from primary research, the study explores how context shapes informal relations in three case studies of intergovernmental relations: the Agreement on Internal Trade, the Health Care Innovation Working Group, and the Ministerial Conference on the Canadian Francophonie. By focusing on variables at various levels, one can better understand how informality operates in a given context. The study makes two central arguments: first, that informality should not be equated with disorder. By examining the environment in which informal relations occur, one can better understand the effects of those relations. Second, while informal relations are important, this importance must also be understood in context: informal relations have effects on the speed and efficiency of work among public servants, but the environment in which they occur plays an important role in limiting the effects of informality. Thus, the effects of informal relations are shaped by context. Informal relations are present and ‘important,’ but although they are ‘informal,’ they are still structured by the environment of Canadian federalism.