Sustainable urban development calls for a balanced package of conditions that induce a high quality of life (including safety and security) in cities. We argue that modern cities have to develop knowledge- based strategies for smart, safe and sound (3-S) city development, supported by urban performance assessment (UPA) as a framework for sustainable urban planning. The present study builds on these strategic notions and articulates the message that smart urban policy should look into input resources in relation to output performance. Particular attention will be paid to the constituents and the role of multiple safety indicators in urban performance analysis. Next, an appropriate method from the industrial management literature, namely, super-efficient data envelopment analysis (SE-DEA) will be utilized in order to undertake a comparative performance assessment of safety conditions in 57 world cities, followed by a similar analysis for 14 large European cities. Both world-wide and Europe-wide, there appear to be significant differences in safety performance of cities, which means that there is much scope for strategic and effective safety policy in many cities.