This book constitutes the thoroughly refereed post-conference proceedings of the 9th International Symposium on Foundations and Practice of Security, FPS 2016, held in Québec City, QC, Canada, in October 2016. The 18 revised regular papers presented together with 5 short papers and 3 invited talks were carefully reviewed and selected from 34 submissions. The accepted papers cover diverse research themes, ranging from classic topics, such as malware, anomaly detection, and privacy, to emerging issues, such as security and privacy in mobile computing and cloud.