Search-based Software Engineering (SBSE) is a research area focused on the formulation of software engineering problems as search problems, and the subsequent use of complex heuristic techniques to attain optimal solutions to such problems. A wealth of engineering challenges – from test generation, to design refactoring, to process organization – can be solved efficiently through the application of automated optimization techniques. SBSE is a growing field – sitting at the crossroads between AI, machine learning, and software engineering – and SBSE techniques have begun to attain human-competitive results. The Symposium on Search-Based Software Engineering is a venue dedicated to the SBSE research field. The 12th symposium will be held this year in Bari, Italy, co-located with the Empirical Software Engineering International Week (ESEIW 2020).