Changes in birth rates profoundly influence society for decades as larger or smaller groups move through school, adulthood, work force, and finally into retirement. A striking change in the youth experience is an apparent lengthening of the transition period from youth to adult. Several symptoms mark this phenomenon. Women begin marriage and childbearing at older ages. More young adults live with their parents longer. More people are going to college than ever. While the average size of the family has dwindled in recent years, its average income has stabilized. While youths survive to age 24 more than ever before, they still suffer their share of health problems. Yet more and more, these problems stem from behavior rather than disease. A much higher proportion of students are completing high school today than in the 1950s. Data on voting behavior show that only 36 percent of 18- to 24-year olds voted in the 1988 Presidential elections; 61 percent of older persons voted in that election. 59 tables, 59 figures, and index