Resumen: This article focuses on the effect of urbanization on violent crime - particularly homicide in Costa Rica. Although violence is a major problem throughout Latin America, few empirical studies carried out in the area use high-quality socioeconomic and crime databases with a high level of geographical disaggregation. In this article, we employ data from all 473 districts of Costa Rica between 2010 and 2013. We develop a model which takes into account endogeneity problems and uses contrasts of marginal linear predictions. We conclude that the degree of urban concentration plays a key role in explaining homicide rates, other things being equal. This effect is progressive: the greater the urban concentration, the greater the increase in homicide rates. This causal relationship is not observed in offenses other than homicide. Idioma: Inglés DOI: 10.1590/dados.2021.64.1.225 Año: 2021 Publicado en: DADOS-REVISTA DE CIENCIAS SOCIAIS 64, 1 (2021), [35 pp] ISSN: 0011-5258 Factor impacto JCR: 0.545 (2021) Categ. JCR: SOCIAL SCIENCES, INTERDISCIPLINARY rank: 99 / 112 = 0.884 (2021) - Q4 - T3 Factor impacto CITESCORE: 0.6 - Social Sciences (Q3)