This volume contains the papers presented at PARIS-18: Workshop on Programming And Reasoning on Infinite Structures held on July 7-8, 2018 in Oxford. Together with the 9 papiers included here, the workshop program will also contain three invited talks by Bahareh Afshari (University of Gothenburg), James Brotherston (University College London) and Pierre Hyvernat (Savoie Mont-Blanc University).

The workshop aims at gathering researchers working on those topics as well as colleagues interested in understanding those recent results and open problems of this line of research. For outsiders, the workshop will offer tutorial sessions and survey-like invited talks. For specialists of the topic, the workshop will permit to gather people working with syntactical or semantical methods, people focusing on proof systems or programming languages, foster exchanges and discussions benefiting from their various perspectives.

We would like to thank the PC members, the authors of contributed papers as well as FLOC chairs and the organization team. PARIS workshop is partially funded by the ANR projet RAPIDO (ANR-14-CE25-0007). Last but not least, let us mention the excellent work achieved by EasyChair team maing the life of PCs member, authors and program chairs much simpler.