Currently there are no comparative studies to measure on a global basis social policy as a government input. An alternative is the inclusion of various relevant indicators for social policy in a single index, which allows a statistical and comparative analysis of different countries. The United Nations in 2006 proposed a tool to measure social policies in different countries called Social Policy Index (SPI), which results are not yet known. The aim of this study was to determine the feasibility of measuring social policy based on their inputs and applying the Social Policy Index (SPI) in three countries with different welfare systems, establishing a retrospective comparison of the situation of social policies of each one considering the years 2005-2010. The results show consistency between the value obtained by the SPI and the socioeconomic and political context of each country, and their classification in different welfare regimes, so it is an index that could be used as a tool for measuring and comparing social policies.