A Census of Population based on an administrative Register

One of the main characteristics of the 2001 Spanish Census of the Population was the use of an administrative Register of Population (El Padrón) for pre-printing the questionnaires and also the enumerator's record books of the census sections. In this paper we present the main characteristics of the relationship between the Population Register and Census of Population, and the main changes that are being foreseen for the next Census that will take place in 2011.