The MST workshop series is meant to bring together researchers, professionals, and industrial engineers with an interest in the technologies for mobile systems. The third edition offers a comprehensive view on architecture models, technology trends, and memory solutions enabling personal and industrial mobile systems, including smartphones, tablets, smartwatches, IoT devices. The interest is on the role that memory and storage subsystems play upon system performance, energy, dependability, security, and functionalities. Confirmed speakers include experts from leading companies and universities, among which Micron, ARM, Sierra Wireless, Phison, Politecnico di Milano, Politecnico di Torino, Nanyang Technological University, Eurecom, ALaRI, ETH Zurich, University of Napoli Federico II. MST 2017 is organized by Fondazione Politecnico di Milano and sponsored by Micron Foundation, Politecnico di Milano and AEIT/AMES.