This book constitutes the refereed proceedings of the 15th International Conference on Combinatorics on Words, WORDS 2025, held in Nancy, France, during June 30– July 4, 2025.

The 20 papers included in these proceedings were carefully reviewed and selected from 31 submissions. They focus on mathematical theory of words. In particular, the combinatorial, algebraic and algorithmic aspects of words are emphasized.

This book constitutes the refereed proceedings of the 15th International Conference on Combinatorics on Words, WORDS 2025, held in Nancy, France, during June 30– July 4, 2025.

The 20 papers included in these proceedings were carefully reviewed and selected from 31 submissions. They focus on mathematical theory of words. In particular, the combinatorial, algebraic and algorithmic aspects of words are emphasized.