The series of Summer Schools on Foundations of Programming and Software Systems (FoPSS) was jointly created by EATCS, ETAPS, ACM SIGLOG and ACM SIGPLAN. The first FoPPS was organized in 2017. The goal is to introduce the participants to various aspects of computation theory and programming languages. The school, spread over a single week, is aimed at students and researchers in Theoretical Computer Science, broadly construed. Each year the school is focused on a particular, actively researched topic.