This paper argues that better yardsticks for inter-case comparison are indispensable to promote a process of additive insight on Europeanisation. Therefore, operationalisations are suggested here for aspects of both the independent and the dependent "variables" of Europeanisation. The empirical material used in this paper to briefly illustrate the concepts introduced, stems from a collaborative research project that analyses the national transposition, enforcement, and application of six EC labour law Directives in all fifteen member states.