The 56th Annual Symposium on Foundations of Computer Science (FOCS 2015), sponsored by the IEEE Computer Society Technical Committee on Mathematical Foundations of Computing, will be held in Berkeley, California from October 18-20 (Sunday through Tuesday), with a welcome reception Saturday (October 17) evening. Papers presenting new and original research on theory of computation are sought. Typical but not exclusive topics of interest include: algorithms and data structures, computational complexity, cryptography, computational learning theory, computational game theory, parallel and distributed algorithms, quantum computing, computational geometry, computational applications of logic, algorithmic graph theory and combinatorics, optimization, randomness in computing, approximation algorithms, parameterized complexity, algorithmic coding theory, algebraic computation, and theoretical aspects of areas such as networks, privacy, information retrieval, computational biology, and databases. Papers that broaden the reach of the theory of computing, or raise important problems that can benefit from theoretical investigation and analysis, are encouraged.