The PRISMS project analyses the traditional trade-off model between privacy and security and works towards a more evidence-based perspective for reconciling privacy and security, trust and concern. It has examined how technologies aimed at enhancing security are subjecting citizens to an increasing amount of surveillance and, in many cases, causing infringements of privacy and fundamental rights. PRISMS conducted both a multi-disciplinary inquiry into the concepts of privacy and security and their relationships and an EU-wide survey to determine whether people evaluate the introduction of security technologies in terms of a trade-off. As a result, PRISMS will determine the factors that affect the public assessment of the security and privacy implications of a given security technology. The project is using these results to devise a decision support system (DSS) providing users (those who deploy and operate security systems) insight into the pros and cons, constraints and limits of specific security investments compared to alternatives taking into account a wider society context.