The study was motivated by the fact that despite the presence of private security companies and the availability of their services in Nairobi city, there was still an upsurge of insecurity. This study was informed by Situational crime prevention and Crime prevention through environmental design theories. Descriptive survey research design was used, and the study utilized stratified random sampling technique to select respondents from the study population which was 500 respondents. Data were obtained using a combination of a questionnaire and interview schedule. Copies of the questionnaire were administered to 151 respondents, who were drawn from the private security companies in the area of study, and the members of staff working in the private institutions and also the area residents. The study was carried out in Karen location which is an upper market estate in Nairobi County. The study identified five categories of crime control services provided by private security companies, with providing alarm response and loss prevention being the major crime control service. The study further found that majority of the residents in the study area goes for the medium level security premium which offers alarm response and security guarding services. Findings revealed that a majority of respondents (52%) perceived the level of effectiveness by private security companies to be fairly moderate, 28% perceived them to be average and 20% of the respondents perceived them to be good. Overall, private security services, were perceived, to be relevant in crime control in Karen location.

Keywords: Crime, Crime Control., Security alarms, Surveillance, access control