Proceedings of the 21st Workshop on Logical Frameworks and Meta Languages: Theory and Practice

This volume of the Electronic Proceedings in Theoretical Computer Science (EPTCS) includes the contributed papers presented at the 21st International Workshop on Logical Frameworks and Meta-Languages: Theory and Practice (LFMTP 2026), in Lisbon, Portugal, on July 24th, 2026, at the Federated Logic Conference (FLoC 2026) as a satellite event of the 11th International Conference on Formal Structures for Computation and Deduction (FSCD 2026). The program committee for this edition of LFMTP was chaired by Olivier Hermant and Sophie Tourret. More information about LFMTP can be found on https://lfmtp.org.