Public Administrations (PAs) are facing profound institutional and organizational changes requiring managers, stakeholders, and responsible statesmen to increase their ability in quick decision making processes. In this context, information related to individual and collective needs plays a large and relevant role, and therefore a deep knowledge of the observed phenomena and an increased degree of timeliness, quality, and efficiency is required. This article presents a case study concerning the development of a Statistical Information System (SIS) out of data coming from administrative archives of the PAs. Such archives are a rich source of up to date information, but an attempt to use them as sources for statistical analysis reveals errors and incompatibilities among each other that do not permit their usage as a statistical and decision support basis. These errors and incompatibilities are usually undetected during administrative use, since they do not affect their day-by-day use in the PAs; however they need to be fixed before performing any further aggregate analysis. In the sequel of the article, the reader is engaged with the basic aspects involved in building a SIS out of administrative data, such as design of an integration model for different and heterogeneous data sources, improvement of the overall data quality, removal of errors that might impact on the correctness of statistical analysis, design of a data warehouse for statistical analysis, and design of a multidimensional database to develop indicators for decision support. Finally, some examples are presented concerning the information that can be obtained by making use of a SIS constructed out of Registry and Income Office archives.