This book constitutes the post-conference proceedings of the 11th International Conference on Critical Information Infrastructures Security, CRITIS 2016, held in Paris, France, in October 2016. The 22 full papers and 8 short papers presented were carefully reviewed and selected from 58 submissions. They present the most recent innovations, trends, results, experiences and concerns in selected perspectives of critical information infrastructure protection covering the range from small-scale cyber-physical systems security via information infrastructures and their interaction with national and international infrastructures.