In 1987, a 40-year longitudinal study followed children from middle-class families and measured their early personalities and temperaments. Those who were emotionally volatile, quick to anger, and low in emotional stability were more likely to experience downward mobility. By midlife, their occupational status matched their peers who had grown up in working-class homes. In other words, early emotional volatility predicted weaker long-term career outcomes, even when the children started in more advantaged environments.