Occupational and career mobility in adulthood is often referred to as intragenerational social mobility. It involves change in an individual's position in the labor market over the adult life course. Change is studied with respect to both type of work and the rewards derived from work. The term career refers to an individual's job history. Empirical regularity in the careers of individuals in the labor force defines what we call a "career line" or "job trajectory," since a work history common to a portion of the labor force reflects the existence of structurally determined linkages among jobs in the economy. Jobs are located in particular firms, whereas occupations and industries encompass jobs in many firms. An individual may remain in the same occupation or industry but change firms (and jobs within the same firm) any number of times. Since the process of...