[2] Haglund received his Ph.D. in 1993 from the University of Georgia, with the dissertation Compositions, Rook Placements, and Permutations of Vectors supervised by Earl Rodney Canfield.
In 2007, Haglund, Haiman and Loehr gave a combinatorial formula for the non-symmetric Macdonald polynomials.
-Catalan Numbers and the Space of Diagonal Harmonics: With an Appendix on the Combinatorics of Macdonald Polynomials.
[6] In 2006, he gave a Plenary Address at the 18th International Conference on Formal Power Series and Algebraic Combinatorics (FPSAC '06), San Diego (USA).
Among the Ph.D. students supervised by Haglund are Frederick M. Butler, Mahir Bilen Can, Logan Crew, Sarah Katherine Mason, Anna Pun, Chunwei Song, and Meesue Yoo.