The 15th volume of ToPNoC contains revised and extended versions of a selection of the best workshop and tutorial papers presented at the 40th International Conference on Application and Theory of Petri Nets and Concurrency, Petri Nets 2019, and the 19th International Conference on Application of Concurrency to System Design, ACSD 2019. The papers cover a diverse range of topics including model checking and system verification, refinement and synthesis; foundational work on specific classes of Petri nets; and innovative applications of Petri nets and other models of concurrency. Application areas covered in this volume are: process mining, verification, formal semantics, communication protocols, business processes, distributed systems, and net synthesis. Thus, this volume gives a good overview of ongoing research on concurrent systems and Petri nets.