This paper evaluates the effects of the installation of security devices on an estate with a high burglary rate. The study considered the burglary rate itself and the residents' feelings of vulnerability to that crime. The researcher used a control estate to determine whether or not other factors would be the cause of any changes. The methodology had two components: first, analysis of 5 years of crime data for the target, the control and the adjacent displacement area; and, second, interviews with residents both before and after the security devices were installed. The installation of security devices had at least a short-term positive effect on residents. The burglary rate on the target estate remained steady, while the control estate and displacement areas had increased rates for that offense. The burglary rate alter rose on the target estate, in part because of insufficient maintenance, a problem that may have stemmed from failure of the residents to report broken devices. Not all residents worried about burglary. After security devices were installed, the number of anxious residents declined. The residents of the control estate became more anxious. Appendixes discuss survey response, data on recorded crime prior to the experiment, the security devices, and statistical methods. Tables, footnotes, and 19 references accompany the text.