To what degree is the course of human life prefigured by the childhood and adolescent years? Clausen draws on 60 years of research from this long-term inquiry into human lives to answer this question. He demonstrates that "adolescent planful competence", a combination of self-confidence, dependability and an investment in intellectual matters has a significant and continuing influence on many aspects of our adult lives, even into old age. Over 300 youngsters born in the 1920s in California's Bay area were studied intensively through their school years and periodically followed up since then. Although the many developments in their lives could not have been forseen, classifications made from data available for their adolescent years enabled Clausen and his colleagues to make predictions of the paths their lives would take. Clausen shows how study members who, during their teenage years, displayed a high degree of planful competence, made more realistic choices early in life and were selected for more promising opportunities as adults than others.
Other aspects of personality, appearance and social background also had long-term consequences, but adolescent planful competence proved far more potent than any other measure in indicating how lives would change, and who would experience essential stable, as opposed to crisis-ridden, lives.