This book constitutes the proceedings of the Third OpenSHMEM Workshop, held in Baltimore, MD, USA, in August 2016. The 14 full papers and 3 short papers presented were carefully reviewed and selected from 25 submissions. The papers discuss a variety of ideas of extending the OpenSHMEM specification and making it efficient for current and next generation systems. This included active messages, non-blocking APIs, fault tolerance capabitlities, exploring implementation of OpenSHMEM using communication layers such as OFI and UCX and implementing OpenSHMEM for heterogeneous architectures.