This research addresses the question of what explains municipal performance in terms of delivering social services and fiscal performance. While the existing literature explains governmental performance with political, institutional and socio-demographic factors, I suggest that the greatest influence on municipal performance comes from having qualified managers. Specifically, I argue that that mayoral qualifications influence municipal performance. By qualifications I mean mayors’ human capital, that is, their educational and job-related experience. The rationale for my proposition rests on the fact that in developing municipalities the mayor is not just the elected leader but also the public manager, as s/he performs not just political but also administrative functions. Under certain circumstances, however, mayoral qualifications may not have the same influential power on municipal performance. Therefore, I also argue that in unfavorable municipal contexts, the potential influence of mayoral qualifications on performance decreases. I use both statistical and survey-experimental methodologies to test the hypotheses derived from the proposed “mayoral quality theory.” I collected six years of data for the statistical analyses by doing field research across the 40 municipalities that comprise the Colombian Department of Norte of Santander. For the surveyexperimental analysis, I gathered data from interviews and surveys with 120 mayors from 12 Latin American countries, who participated in the II Latin American Congress of Cities and Local Governments held in Cali, Colombia, on July 26-29, 2006. The statistical findings reveal that mayoral qualifications—education and jobrelated experience—positively influence municipal performance with respect to education enrollment, tax property collection, and social program investment. However, the positive impact that mayoral qualifications have on such performance indicators decreases under external constraints, such as the presence of illegal armed groups. From the survey-experimental study, findings show that issue salience (or nature of municipal need) moderates the impact that mayoral qualifications have on mayors’ decision-making. In education issues, for example, qualified mayors are more likely to perform better, while in infrastructure issues they are less likely to do so.