Edited under the auspices of the Association of Logic, Language and Information (FoLLI), this book constitutes the refereed proceedings of the 20th anniversary of the International Conference on Logical Aspects of Computational Linguistics, LACL 2016, held in LORIA Nancy, France, in December 2016. The 19 contributed papers, presented together with 4 invited papers and 6 abstracts, were carefully reviewed and selected from 38 submissions. The focus of the conference is the use of type theoretic, proof theoretic, and model theoretic methods for describing and formalising natural language syntax, semantics, and pragmatics as well as the implementation of the corresponding tools.