The World Health Organization definition for active ageing and the approach and measurement made by the UNECE/EC to define an Active Ageing Index (AAI) are the starting points for this work. This paper reflects on the proposed methodology of the European AAI for measuring and adapting it to sub-national spaces, in this case Spain and its regions. Consistently, evaluation of specific data sources and indicators that can be built from them, trying to homogenise with the national-level AAI, according to its calculation methodology, are also essential objectives of this paper. In general, Spanish data sources are broadly similar to those which have been used for calculating the AAI in Europe, while some limitations, difficulties for homogenization and distortions are inevitable due to the AAI specificity. These factors have conditioned the calculation of some indicators, tentatively replaced by other alternatives and approximations. The AAI for Spain, calculated on the basis of Spanish data sources, is consistent with the European AAI, although slightly lower. However, it is closely connected with other general indicators in Spain (Gross Domestic Product, Synthetic Quality of Life Index, New Index of Human Development) to differentiate the level of economic and social development of the Spanish regions. The future development of the AAI in Spain requires delving into the use of more adequate indicators and weights, and more crucially advancing its usefulness to assess the public policies for the elderly in Spain. In addition, it aims to extend its use to certain Latin American countries.