This chapter discusses how a geographic information system (GIS) and spatial analysis are used to model the relationship between the daily routine activities of youth and rates of violence, and provides an example of how these techniques can be applied to analytical studies examining violence in places. Most research informing hotspots and related crime prevention efforts focuses on the contribution of places and the physical environment to crime levels. Yet very little is known about how time influences patterns of crime across places and environments. This chapter discusses how time of day, week and year can be incorporated into spatial analysis of crime patterns to further inform crime prevention. A model of opportunity factors is developed to predict the spatial and temporal relationship among violence, schools, youth hangouts, retail properties and neighborhood disorganization across census blocks. Instrumental variables regression is used to estimate spatial lag models of violence.