Environmental Criminology views discrete criminal events as enfolded, like the layers of an onion, in expanding layers of spatial, temporal, perceptual, and social context. The dimensions of crime are vectors of analysis to be followed across the layers, either inward from the widest possible context layer toward the discrete crime, or outward from the discrete crime to ever broader contexts. Any particular layer forms a field of intersecting dimensions in which the crime pattern can be analyzed. Each field forms a "landscape" that changes across a "time scape." Analysis for crime prevention is a process that focuses on the intersection of motivation and opportunity. Opportunity influences motivation and motivation influences the perception of opportunities. Crime prevention that uses Environmental Criminology attempts to separate potential offenders from suitable targets or good opportunities by changing the attraction of activity nodes, the travel paths of potential offenders and potential victims, and the character of neighborhood edges. When nodes, paths, and edges cannot be influenced at high levels of spatial and temporal aggregation, then Environmental Criminology, in conjunction with situational crime prevention, looks for ways to reduce the offender's perception of "good" targets. This is often accomplished by techniques that increase the amount of work required and the quantum of risk assumed in doing a particular crime at a particular place and time. 2 figures and 106 references