Spain is one of the European countries with more municipalities adhering to the Local Agenda 21 (LA21). Environmental spending exerts a great influence on implementing LA21. But some authors raise doubts about the firm commitment of local governments to LA21 objectives.

Thus, the main objective of this paper is to verify whether political commitment is backed up with action towards meeting the objectives of sustainable development by means of budgetary support for waste management policies.

To accomplish this, we applied the Difference in Differences technique for the period 2002-2012 in the Spanish municipalities. Our initial results confirmed the original hypotheses and showed that local governments that adhered to LA21 were genuinely committed to achieving at least one LA21 goal and offering greater budgetary support for waste management. However, the sensitivity analysis revealed unexpectedly ambiguous evidence about the research question, in that we observed a great volatility of results depending on the sample and dependent variables chosen.