This document provides a summary of the "Workshop on Internet of Things (IoT) Semantic Interoperability (IOTSI)", which took place in Santa Clara, California March 17-18, 2016. The main goal of the workshop was to foster a discussion on the different approaches used by companies and Standards Developing Organizations (SDOs) to accomplish interoperability at the application layer. This report summarizes the discussions and lists recommendations to the standards community. The views and positions in this report are those of the workshop participants and do not necessarily reflect those of the authors or the Internet Architecture Board (IAB), which organized the workshop. Note that this document is a report on the proceedings of the workshop. The views and positions documented in this report are those of the workshop participants and do not necessarily reflect IAB views and positions.