This book constitutes the refereed proceedings of the 4th Workshop on Causal Discovery, CADIS 2026, held in Tonantzintla, Mexico, during November 30 – December 1, 2026.

The 11 full papers, 1 short paper, 2 invited keynotes and 1 paper abstract included in this volume were carefully reviewed and selected from 14 submissions. The papers cover the following topical sections: Fundamentals and Algorithms for Causal Discovery; and Applications.