Thomas R. Frieden, MD, last week became the 16th director of the Centers for Disease Control and Prevention and administrator for the Agency for Toxic Substances and Disease Registry. He was named director of CDC by the White House and the Department of Health and Human Services on May 15. Frieden, 48, has been the director of the New York City Health Department since 2002. He replaces Richard Besser, MD, who has been the acting CDC director and acting ATSDR administrator since mid January.