This book constitutes the refereed proceedings of the Workshops and Symposiums of the 15th International Conference on Algorithms and Architectures for Parallel Processing, ICA3PP 2015, held in Zhangjiajie, China, in November 2015. The program of this year consists of 6 symposiums/workshops that cover a wide range of research topics on parallel processing technology: the Sixth International Workshop on Trust, Security and Privacy for Big Data, TrustData 2015; the Fifth International Symposium on Trust, Security and Privacy for Emerging Applications, TSP 2015; the Third International Workshop on Network Optimization and Performance Evaluation, NOPE 2015; the Second International Symposium on Sensor-Cloud Systems, SCS 2015; the Second International Workshop on Security and Privacy Protection in Computer and Network Systems, SPPCN 2015; and the First International Symposium on Dependability in Sensor, Cloud, and Big Data Systems and Applications, DependSys 2015. The aim of these symposiums/workshops is to provide a forum to bring together practitioners and researchers from academia and industry for discussion and presentations on the current research and future directions related to parallel processing technology. The themes and topics of these symposiums/workshops are a valuable complement to the overall scope of ICA3PP 2015 and give additional values and interests.