Although there are no reliable statistics on the number of homeless youth, because there is no standard definition of this population and it is difficult to find and count, this report offers best estimates. For youth ages 12-17, two estimates from very different sources are in the range of 1.6 to 1.7 million a year (between 7 and 8 percent of all youth in these age ranges). For 18- to 19-year-olds the estimate is 80,000 to 170,000 annually (5 percent of this age group in the general population). Those age 20 to 24 are estimated at approximately 124,000 to 236,000 annually (7 percent of this age group in the general population). In shelter samples, the proportion of males and females tend to be about equal. For older samples and “street” samples, males are more prevalent. Race/ethnicity distributions depend on the race/ethnicity of the community in which homelessness occurs. The proportion of homeless youth who are gay, lesbian, or bisexual varies from a low of approximately 6 percent served by youth centers to as high as 11-35 percent in street samples. Homeless youth are three times as likely as national samples of youth to be pregnant, to have impregnated someone, or to be already a parent. Youth in runaway and homeless shelters tend to have been homeless only once and for a short period. Risk factors for homelessness are school difficulties, substance abuse, mental health problems, family conflict and child maltreatment, out-of-home placement and foster care, and juvenile justice involvement. Intervention points are those surrounding institutional release (youth most at risk). 3 tables and 9 references