This book constitutes the refereed proceedings of the 18th International Conference on Reversible Computation, RC 2026, held in Turin, Italy, during July 9-10, 2026.The 13 full papers, 3 work-in-progress papers and 1 tool demonstration paper were carefully reviewed and selected from 38 submissions. They were organized in topical sections as follows: Models of Reversible and Quantum Computation; Formal Developments in Reversible and Quantum Programs; and Support for Reversible Programming.