Molecular biologists Michael Grunstein, PhD, of the University of California, Los Angeles (UCLA), and C. David Allis, PhD, of The Rockefeller University have been pioneers in identifying and describing how histone modifications and chromatin structure affect gene regulation. Their groundbreaking discoveries not only revolutionized our understanding of molecular biology, but also were instrumental in launching the modern study of histones in epigenetics, with broad implications for human health and disease.