Which societies are prone to be compliant with tax laws? Who is willing to pay more for social solidarity? Based on recent surveys in Argentina and Chile, this research paper contrasts two similar countries that show remarkable differences in tax compliance and commitment to social policies. The analysis of the data supports the hypothesis that social variables associated with trust and legitimacy have an independent effect on social solidarity. By extending standard economic models, I argue that paying taxes is also partially contingent on social values, and on the perceived institutional performance of the public sector.