ESEM is the premier conference for presenting research results related to empirical software engineering. ESEM provides a stimulating forum where researchers and practitioners can present and discuss recent research results on a wide range of topics, in addition to exchanging ideas, experiences and challenging problems. The 15th edition of ESEM will be held in Bari, Italy, from September 20th to 24th, 2021 as part of the Empirical Software Engineering International Week with other co-located events.