The 4th International Symposium on Polybenzoxazines ISPBZ 2020 will take place in Luxembourg on 23-25 September 2020. The symposium will focus on polybenzoxazines, reporting on the most recent advances in our understanding of the common properties of benzoxazine, as well as the latest progresses towards their technological exploitation. Polybenzoxazines are an emerging family of polymers finding applications in high technology fields, thanks to their many outstanding properties compared to conventional phenolic resins, such as excellent heat and chemical resistance, flame retardancy, a low dielectric constant, good dynamic mechanical properties, and a relatively inexpensive cost. The field of applications of polybenzoxazines is in full expansion, for instance as components of self-healing systems due to supramolecular interactions. In the coming years this area of research, between fundamental and applied science, is expected to give additional insights into the properties of polybenzoxazines and to unveil unforeseen applications for these materials.