The aim of this paper is to propose a systems interpretation of the concept of complexity and its implications for a theoretical discussion of the concept of boundary in complex service systems. The proposal highlights the interpretative contribution of a dual perspective of observation that distinguishes between a structure-based view and a systems- based view. When dealing with complexity, the phenomenon under investigation cannot be addressed through management approaches that aim to measure and control it in a vain attempt to find the best solution. Due to the inner nature of complexity, a more rewarding approach to a full understanding of problematic situations should place consolidated management models within a more general interpretation framework that suggests preliminary insights about the real nature of the investigated phenomenon. First, this paper outlines the theoretical background of the literature on service, service systems and complex service systems, providing evidence of the contribution of recent service research advances such as service science and service-dominant logic. Next, the paper focuses on the basic principles of systems thinking to introduce the Viable Systems Approach (vSa) as a general framework of reference for bot hthe investigation and the governance of social organisations. The vSa conceptual framework is adopted fo proposing some reflections from a systems perspective in the investigation of the case of the London Borough of Sutton (LBS). The focus is on interpreting the paradoxical situation of an increased fear of crime among LBS residents despite the evidence of reduction in the crime rate. Although the incidence has fallen for most types of crimes, a recent poll confirmed that crime is still rated as the most important issue for residents. Therefore, improving safety and reducing crime remain the top priorities for the Safer Sutton Partnership Service. In short, this study proposes to consider ‘‘reducing the fear of crime in a community’ as a complex service system.