This book constitutes the refereed proceedings of the 4th International Conference on Autonomic and Trusted Computing, ATC 2007, held in Hong Kong, China in July 2007, co-located with UIC 2007, the 4th International Conference on Ubiquitous Intelligence and Computing.The 55 revised full papers presented together with 1 keynote lecture were carefully reviewed and selected from 223 submissions. The papers are organized in topical sections on cryptography and signatures, autonomic computing and services, secure and trusted computing, autonomic models and architectures, trusted models and systems, intrusion detection, access control, trusted computing and communications, key management, worm detection and data security, secured services and applications, as well as fault-tolerant systems.