Despite the growing interest in private security amongst academics in recent years there have been relatively few empirical studies at a micro level. This thesis presents the findings of a detailed study of two locations or nodes of governance where security officers were the main agents of policing. In-particular the research focuses upon the legal powers security officers have and use in undertaking their roles in the two research sites. The first stage of the research sought to identify what legal tools security officers possess and in answering this question the thesis identifies different models of security officer based upon the legal tools available to them. The second stage of the research focused upon two case study sites: a retail leisure facility called Pleasure Southquay and a manufacturer of defence equipment called Armed Industries. Using a methodology based upon structured and semi-structured interviews, documentary data as well as observation the thesis presents findings illustrating the importance of security officers, suggesting that despite a general image of them as 100v status and ineffective, in their workplaces they are 'big fish in small ponds', particularly when viewed in terms of the broader systems of security that arc utilised. It also demonstrates how they generally have a good knowledge of the limits of their legal tools and how to make use of them lawfully. The research also elucidates how security officers usc some of their tools such as to arrest, use force, to search and to exclude, amongst others, and how the extent to which these arc used varies amongst officers. In usi ng these too Is 0 fficcrs arc also frequent 1y con fronted with di fficult and sometimes dangerous situations that lead to verbal abuse, threats of violence as well as assault amongst other occupational hazards. The research also draws out some of the characteristics of the culture of security officers and the different orientations that exist and how this impacts upon the lise of certain legal tools and ultimately the effectiveness of security officers.