University of Miami, Miami, Fla: L. Friedman; L. Pall. Montefiore Medical Center, Bronx, NY: D. Futterman; D. Monte; M. Alovera-DeBellis; N. Hoffman. Children's Hospital of Philadelphia, Philadelphia, Pa: B. Rudy; D. Schwarz; M. Tanney. Children's Hospital of Los Angeles, Los Angeles, Calif: M. Belzer; D. Tucker. Children's National Medical Center, Washington, DC: L. D'Angelo; C. Trexler; C. Townsend-Akpan; R. Hagler. University of Maryland, Baltimore: L. Peralta; G. Ryder; S. Miller; K. Feroli. Tulane Medical Center, New Orleans, La: S. E. Abdalian; D. Foxworth; L. Green. Children's Hospital, Birmingham, Alabama: M. Sturdevant; A. Howell. St Jude Children's Research Hospital, Memphis, Tenn: P. Flynn; K. Lett. Children's Diagnostic and Treatment Center, Fort Lauderdale, Fla: A. Puga; D. Cruz. Cook County Hospital/University of Chicago, Chicago, Ill: L. Henry-Reid; R. Camacho; M. Bell; J. Martinez; D. Johnson. Mt Sinai Medical Center, New York, NY: L. Levin; M. Geiger. Emory University, Atlanta, Ga: M. Sawyer; G. Walls. State University of New York Health Science Center, Brooklyn: J. Birnbaum; M. Ramnarine. University of Medicine and Dentistry of New Jersey, Newark: P. Stanford; F. Briggs. The following investigators have been responsible for the basic science agenda: Children's Research Institute and the George Washington University School of Medicine, Washington, DC: C. Holland. University of California at San Francisco: A. B. Moscicki. University of California at Los Angeles: D. Murphy. University of Alabama at Birmingham: S. H. Vermund. University of Colorado, Denver: R. Booth. University of Pittsburgh, Pittsburgh, Pa: P. Crowley-Nowick. University of Pennsylvania, Philadelphia: S. D. Douglas. University of Alabama at Birmingham: C. Wilson; C. Partlow. Westat, Inc, Rockville, Md: B. Hobbs; J. Ellenberg; L. Paolinelli; L. Muenz; T. Myers; A. Sheon; Rick Mitchell. National Institute of Child Health and Human Development, Bethesda, Md: A. Rogers; A. Willoughby. National Institute on Drug Abuse, Bethesda: K. Davenny; V. Smeriglio. National Institute of Allergy and Infectious Diseases, Bethesda: E. Matzen; J. Lew. Health Resources and Services Administration, Rockville, Md: G. Weissman.