For two decades now, experiences in decentralization and federalization have been in progress in many countries, particularly in Sub Saharan Africa. How can these processes be understood and improved? Focusing on four Sub-Saharan countries (Burkina Faso, Ghana, Kenya and Senegal), this volume applies an original approach to address such questions. No attempt is made to transpose an ideal Western model - which does not exist. Here, decentralization is viewed as a sequential process, implying choices that are the sole responsibility of the country concerned. For each of the four countries, the authors provide a diagnosis of how decentralization is organized in practice and compare this with the institutional architecture adopted. This analysis of the gaps separating what is formally targeted and what has been achieved on the ground suggests possible directions for reform. A guide for analyzing decentralized policies is proposed, which is useful to help identify the issues at stake, point out stumbling blocks and ensure the coherence of decisions on decentralization.