Routine activity theory, first formulated by Lawrence E. Cohen and Marcus Felson (1979) and later developed by Felson, is one of the most widely cited and influential theoretical constructs in the field of criminology and in crime science more broadly. In contrast to theories of criminality, which are centered on the figure of the criminal and the psychological, biological, or social factors that motivated the criminal act, the focus of routine activity is the study of crime as an event, highlighting its relation to space and time and emphasizing its ecological nature and the implications thereof.In their initial formulation, Cohen and Felson postulated that changes in the structure of the patterns of daily activity of people in cities following World War II could explain the rise in crime that had occurred, according to leading studies at the time. Their hypothesis was that postmodernity had facilitated the convergence in space and time of likely offenders with the goal of committing crimes against suitable targets in the absence of capable guardians. From this they derived two apparently simple ideas with significant implications: first, that the opportunity for crime may depend on a configuration of distinct (though not disaggregated) elements of the aggressor or criminal; second, a correlate of the first, that the absence of either of the first two elements (aggressor and target) or the presence of the third (capable guardians) would be sufficient in itself to prevent a potential criminal event.Routine activity theory is, in short, an attempt to identify, at a macro-level, criminal activities and their patterns through explanation of changes in crime rate trends (Cohen & Felson, 1979). It is based on criminal events, on the distribution and grouping in space and time of the minimal elements that make them up, rather than on the search for offenders' motives, and it thus offers a frame of reference for concrete and individualized crime analysis and facilitates the application The Encyclopedia of Theoretical Criminology, First Edition. Edited by J. Mitchell Miller.