This book constitutes the refereed proceedings of the 10th International Symposium on Search-Based Software Engineering, SSBSE 2018, held in Montpellier, France, in September 2018. The 12 full papers and 7 short papers presented together with 3 keynotes, 2 tutorials, and 1 anniversary paper were carefully reviewed and selected from 21 submissions. SSBSE welcomes not only applications from throughout the software engineering lifecycle but also a broad range of search methods ranging from exact Operational Research techniques to nature-inspired algorithms and simulated annealing. Chapter "Deploying Search Based Software Engineering with Sapienz at Facebook" is available open access under a Creative Commons Attribution 4.0 International License via link.springer.com.