The 13th ACM-IEEE International Conference on Formal Methods and Models for System Design will be held at UT Austin September 21-23, 2015, in conjunction with FMCAD'15, SAT'15, DIFTS'15 and ACL2'15. Over the last decade, the boundaries between computer system components, such as hardware, software, firmware, middleware, and applications, have blurred. This evolution in system design and development practices led in 2014 to a change in the title and scope of the MEMOCODE conference from its original focus on hardware/software co-design to its new focus on formal methods and models for developing computer systems and their components. MEMOCODE's objective is to emphasize the importance of models and methodologies in correct system design and development, and to bring together researchers and industry practitioners interested in all aspects of computer system development, to exchange ideas, research results and lessons learned.