This chapter presents the methodological strategy of the book for studying which combination of sociological, economic, institutionalist, functionalist and rational-choice factors led to the (i) coming into existence, (ii) increase, (iii) decrease and (iv) disappearing of (1) legislative autonomy demands by regionalist parties, of (2) legislative autonomy demands by traditional parties and of (3) legislative autonomy statutes themselves. Doing so, it first clarifies the outcomes under study: how autonomy demands by regionalist and traditional parties, and how the conferral of autonomy by the state are measured. Secondly, it clarifies which factors are taken into consideration when analysing the evolution of those autonomy demands and statutes. Thirdly and finally, it presents the method of analysis, a Qualitative Comparative Analysis (QCA) rendered suitable for longitudinal comparisons, and operationalises the outcomes and conditions under analysis.