This article is about the research with the same name than this paper, granted by the II Investigation Ring in Social Science in March 2008 by CONICYT. The research question is How to approach urban crime and violence phenomena? To answer the research question we focus on the conceptual framework provided by Ecological Theory of Crime and the "neighborhood collective efficiency" concept. The research expects to produce relevant knowledge about the subject based on empirical evidence that would significantly allow contributing to integral public policies design that deal with varied aspects that are part of citizen security.