Testing Broken Windows Theory in Mexico City Carlos J. Vilalta, Center for Research in Geospatial Information Sciences (CentroGeo) Pablo Lopez, Center for Research in Geospatial Information Sciences (CentroGeo) Gustavo Fondevila, Center for Economic Research and Education (CIDE) Oscar Siordia, Center for Research in Geospatial Information Sciences (CentroGeo) Objectives. To test the broken windows theory in the Mexican context. Methods. Publicly available homicide counts and census data at the neighborhood level were used. Broken windows theory was operationalized through the use of social disorder and physical disorder measures. Measures were both calculated using PCA. For data analysis, we employed four multilevel random intercept models to relate homicide counts to our broken windows components. Results. The social disorder and physical disorder components cannot be seen as operating independently from each other. In addition, the negative interaction term between the two components suggests that the combined impact of social disorder and physical disorder is less than the independent effects, and that the impact of social disorder diminishes as neighborhoods become less physically disordered and vice versa. Conclusion. Findings demonstrate the validity of broken windows theory across countries and offer new ideas to support crime prevention policy. Mexico City is currently going through a homicide crisis. The city has experienced a rise in homicides ranging from 842 in 2015 to more than 1,321 between January and October 2019 (according to the data provided by the National Public Security Secretariat). This trend is coincident with a similar rise in homicides at the national level; however, recent surges in homicidal violence at the national level were not matched with significant rises in Mexico City. In this study, we examine how broken windows theory components impact homicide counts in Mexico City. Broken windows theory states that neighborhood incivilities impact the production of crime through a social-psychological mechanism. Previous studies have divided this theory into two components: social disorder and physical disorder. Physical disorder relates to characteristics of the built environment such as abandoned cars, graffiti, litter, unmaintained vacant lots, etc., while social disorder relates to activities such as drinking in the street, prostitution, domestic violence, etc. In this sense, Mexico City is a place with many signs of disorder and the perfect place for testing criminological theories given its crime problem. Previous studies have found that social disorder and physical disorder, as separate com- ponents of broken windows theory, affect homicide, among many other crimes. However, they have not examined whether these theoretical components accurately describe homi- cide patterns in Mexico City, nor have examined whether these components interact with Direct correspondence to Carlos J. Vilalta, Center for Research in Geospatial Information Sci- ences (CentroGeo), Contoy 137, Lomas de Padierna, 14240 Ciudad de M´ exico, CDMX, Mexico 〈cvilalta@centrogeo.edu.mx〉. SOCIAL SCIENCE QUARTERLY C  2019 by the Southwestern Social Science Association DOI: 10.1111/ssqu.12760