The children of immigrants constitute the most consequential and lasting legacy of the new mass immigration to the United States. By the end of the 20th century, over 30 percent of the immigrant population of the United States resided in California, but over 40 percent of under-18 children of immigrants lived in California. Hence, the size and concentration of this emerging population, added to its diverse national and socioeconomic origins and forms of adaptation, make its present evolution extraordinarily important. This chapter was prepared for a volume commissioned by the National Research Council and Institute of Medicine to ascertain the current circumstances, health and development of children of immigrants in the United States. It presents the latest results of a comprehensive longitudinal study of the educational performance and social, cultural, and psychological adaptation of children of immigrants growing up in San Diego, California. The principal nationalities represented in the sample are Mexican, Filipino, Vietnamese, Laotian, Cambodian, and smaller groups of other children of Asian and Latin American immigrants. The data are drawn from the Children of Immigrants Longitudinal Study (CILS), which followed the progress of a large sample of teenagers who were originally interviewed in junior high when most were 14 or 15 years old, and again when they had reached the final year of senior high school and were making their passages to adulthood, firming up plans for their future as well as their outlooks on the surrounding society. The chapter examines a wide range of findings from that latest survey, focusing on changes observed over time — in their family situation, school achievement, educational and occupational aspirations, language use and preferences, ethnic identities, experiences and expectations of discrimination, and social and psychological adaptation — among youth in the San Diego longitudinal sample, and also on two key indices of psychological well-being: self-esteem and depression.