Call it the work world equivalent of the tortoise and the hare.

To determine the impact of career mobility on worker's wages, sociologist Sylvia Fuller of the University of British Columbia examined data from the 1979 National Longitudinal Survey of Youth, tracking nearly 6,000 workers during their first 12 years in the labor market. Despite the frequent job moves made by young Americans today, Fuller's research suggests that workers who frequently change jobs generally end up earning less than their more stable counterparts.

"The past 30 years have seen the erosion of long-term employment, and young people are increasingly told to expect ongoing employer changes throughout their careers," said Fuller. "However, this research examines the cumulative changes workers make, or are forced to make, and demonstrates that these career moves may not always result in higher earnings."

Any benefits of job mobility accrue mainly in a worker's early career. Both men and women typically experience substantial mobility during their early careers, although women change employers slightly less frequently than men. Mobility can be a wage asset when it is concentrated in the early years of employment and not coupled with layoffs, discharges, employment gaps or family-related leave. In this case, moderate or even high levels of mobility can lead to equal or better wage outcomes than stability. But aside from this exception, wage outcomes deteriorate as mobility increases.

One reason for lower wage trajectories among high-mobility workers is their failure to accumulate valuable early tenure associated with staying up to five years with an employer. In the first five years of a job, each year of tenure is associated with approximately 2.4 percent higher wages for men and 2.9 percent higher wages for women.

Fuller also found that high-mobility workers tend to spend a greater proportion of time not employed and, all else being equal, a greater proportion of their job changes are the result of layoffs. Men are laid off or discharged more frequently than women, yet they leave jobs for family reasons less often. Regardless of gender differences, these reasons for job changes--layoffs, discharges and leave for family reasons--are all cause for lower wages because they tend to result in periods of unemployment.

The study findings were published in the American Sociological Review, the flagship journal of the American Sociological Association.