Supporters and practitioners of CPTED believe that crime can be reduced by designing buildings and outdoor spaces so that certain criminal behaviors will be reduced by increasing potential offenders' fear of being observed and apprehended. The interviews found that CPTED advocates perceive crime-related risk as foreseeable danger; i.e., they anticipate how various design features of outdoor spaces and buildings may encourage or discourage specific criminal behaviors. Another objective of CPTED supporters is to provide an unbiased, objective means of distinguishing potential offenders who enter a space from legitimate users of the space. This would increase potential offenders' fear of detection. A third principle of CPTED advocates is that legitimate users of a particular space must act as intended to prevent crime; i.e., they will use the design to increase their opportunity to observe and act appropriately when they perceive suspicious people and behavior. Thus, the implementation of CPTED depends upon its practitioners convincing clients that they understand how criminals are encouraged or discouraged from committing crimes by space design. They must also devise realistic and objective means for users of the space to distinguish potential offenders from law-abiding users of the space; and they must convince legitimate users of the space that they are responsible for behaving in such a way that potential criminals are identified and deterred from committing crimes in the space. The implementation of CPTED thus depends upon the credibility and persuasiveness of practitioners in getting clients to go along with their design recommendations. These findings are based on semistructured interviews with 25 CPTED practitioners and supporters across southern Ontario, Canada. 17 notes and 76 references