Study Aims: to analyze the significant relationship contribution of Individual Microentrepreneurs (MEI) in the socioeconomic development of São Paulo municipalities in the period from 2010 to 2014. Methodology: quantitative approach, of an explanatory nature, with documentary research on data from 637 municipalities in the state of São Paulo. Based on the studies by Silva & Porto Júnior (2006) and Caldarelli & Perdigão (2018), the Gross Domestic Product (Municipal GDP) and the Firjan Municipal Development Index (IFDM) were defined as dependent variables and the total of Existing MEIs per municipality. Main results: there were evidenced positive and significant coefficients of MEI´s in 24 municipalities in São Paulo with low and medium socioeconomic growth, in 2014. Methodological contributions: use of the Quantile Regression technique, more appropriate to estimate independent variables categorized by high variability, as demonstrated in the studies by Hao & Naiman (1949), Santos (2012), Das, Krzywinski & Altman (2019) and Koenker & Hallock (2001). Relevance and originality: the study expands, in part, the understanding of previous studies on the different relationships pointed out between the MEI, the GDP and the IDFM of municipalities in different categories of municipal socioeconomic development. Contributions to management: public managers, from both small and medium or large cities, based on differentiated actions consistent with each context, have a policy of fostering and supporting the creation of micro and small businesses with one of the effective ways to enhance and impact socioeconomic development.