We are delighted to welcome you to the nineteenth edition of the International Workshop on Mobile Computing Systems and Applications -- HotMobile '18. This year continues the tradition of selective, highly interactive workshops that discuss the latest ideas in mobile systems and applications, along with new breakthroughs in underlying technologies. In addition to the technical program and keynote speakers, the program is designed to continue the HotMobile tradition of engaging the audience in deep technical discussions and debates of controversial approaches. The selection of full papers to this workshop was highly competitive. Out of 65 submissions, the technical program committee accepted 19 for publication and presentation, resulting in an acceptance rate of 29%. An in-person PC meeting was held at the Stony Brook University to make final acceptance decisions. The PC members demonstrated a strong commitment to the selection process, not only by submitting high-quality reviews, but by traveling to New York from locations all over the world, including Singapore, Germany, and France. Accompanying full papers are a set of posters and demonstrations of exciting early stage research from the community. Collectively our program spans a rich range of topics including mobile DNA analysis, virtual reality, self-driving cars, new sensing technologies, and the Web. We feel this reflects the strong health, vibrancy and breadth of the mobile computing field.