The City 21 Program in Andalusia (Spain) is a program that provides support and advice to cities and towns in Andalusia which demonstrate their commitment to create a local plan for sustainability by adopting Local Agenda 21 (LA21). LA21 is a program of action through which town councils make a diagnosis of their municipalities and, following a citizen participation plan, define and implement a series of interventions to achieve improved economic, social and environmental performance in their municipalities. In this paper, we analyze the drivers and hindering factors in the implementation of this program in the Andalusian municipalities. The conclusions offer recommendations to improve these processes that can be generalized to other regions facing similar challenges in the sustainable development of villages and towns around the world.