A consensus exists regarding the idea that, in the search for sustainable development (SD), Local Agenda 21 (LA21) is a key tool for implementing a set of sustainability policies at local level. From a consensus of this nature both an important flow of scientific production and a significant degree of real implementation might be expected. However, a review of the literature and a real case-study (Spain) lead us to conclude that although increasing effort is being made in both fields, there is still a long way to go.