In the face of international crime and terrorism, private security together with public policing and the military is playing a crucial role. The domain of private security is a fairly neglected field of study, especially in South Africa, making this investigation a substantial contribution. With the focus on the impact of organisational culture on the levels of service delivery in South Africa's largest security company, Group4 Securicor (G4S), a model is proposed for aligning organisational culture with levels of service excellence within the company. Data was collected by means of a structured questionnaire with a preceding pilot study. The Competing Values Framework (CVF) and the Baldrige criteria served respectively as guideline for the development of the culture and quality sections of the questionnaire. Although organisational culture and service excellence are well-researched topics, no other investigation applies these aspects to the private security industry. The results show that organisational cultural impacts on service excellence in G4S.