The "Morbidity and Mortality Weekly Report" ("MMWR") Series is prepared by the Centers for Disease Control and Prevention (CDC). Data in the weekly "MMWR" are provisional, based on weekly reports to CDC by state health departments. This issue of "MMWR" contains the following studies: (1) Youth Risk Behavior Surveillance--Selected Steps Communities, United States, 2007 (Shari Shanklin, Nancy D. Brener, Laura Kann, Shannon Griffin-Blake, Ann Ussery-Hall, Alyssa Easton, Erica Barrett, Joseph Hawkins, William A. Harris, and Tim McManus); and (2) Youth Risk Behavior Surveillance--Pacific Island United States Territories, 2007 (Jaclynn Lippe, Nancy Brener, Laura Kann, Steve Kinchen, William A. Harris, Tim McManus, and Nancy Speicher). "Youth Risk Behavior Surveillance--Selected Steps Communities, United States, 2007" summarizes results from surveys of students in 26 Steps communities that conducted surveys in 2007. Results from the 26 Steps communities indicated that a substantial proportion of adolescents engaged in health-risk behaviors that increased their likelihood of becoming obese. "Youth Risk Behavior Surveillance--Pacific Island United States Territories, 2007" summarizes results from surveys of students in grades 9-12 conducted in five territories (American Samoa, Commonwealth of the Northern Mariana Islands, Guam, Republic of the Marshall Islands, and Republic of Palau) during January-June 2007. Across the five Pacific Island territories, the leading causes of mortality among all ages include unintentional injuries, including motor-vehicle crashes; cancer; cardiovascular diseases; stroke; and diabetes. Results from the Youth Risk Behavior Survey (YRBS) indicated that high school students in the Pacific Island territories engaged in behaviors that increased their risk for mortality or morbidity from these causes. Individual studies contain footnotes, references, and tables.