This book constitutes the proceedings of the 24th Annual IFIP WG 11.3 Working Conference on Data and Applications Security, held in Rome Italy in June 2010. The 18 full and 11 short papers presented in this volume were carefully reviewed and selected from 61 submissions. The topics covered are query and data privacy; data protection; access control; data confidentiality and query verification; policy definition and enforcement; and trust and identity management.