Welcome to the Fifth Workshop on the Frontiers of Networks: Theory and Algorithms, to be held in coordination with MobiHoc 2017. The workshop will bring together different research communities that utilize analytical methods to model, design and evaluate large scale networked systems. The format of the workshop is to hold invited talks of 30 minutes duration each, and to explore a range of cutting edge topics in the space of communication, routing, scheduling, learning, games and optimization. Each speaker has made significant contributions to their respective areas, and will bring a unique perspective on the topic of interest.