People with high opinions of themselves as teenagers and young adults earn much more in middle age than their less confident counterparts, with the gap particularly marked in those from privileged backgrounds.
This self-confidence translates into earning hundreds of thousands of dollars more over a lifetime, according to a new study by Timothy Judge, a University of Florida management professor.
"There are certainly significant advantages for children growing up with parents who are well-educated and work in professional occupations, but these advantages are especially profound when children are self-confident," said Judge, whose study will be published later this year in the Journal of Applied Psychology.
"Positive self-concept seems to act like an accelerant Ė the fuel to the fire Ė that leads the advantaged in our society to do better."
Working with graduate student Charlice Hurst, Judge analysed data from the National Longitudinal Survey of Youth, a nationally representative sample of 12,686 men and women.
What they found is that for people who lacked self-confidence, socio-economic background made little difference in how much they earned as adults - roughly $7,000 per year.
But for the confident, growing up in more affluent circumstances made a huge difference Ė roughly $28,000 annually.
What's more, self-assured individuals whose parents were professionals earn much more than self-confident people whose parents were laborers, and for that matter, more than those who lacked self-confidence.
"If your parents are doctors or lawyers, a positive self-concept matters a whole lot more than if your parents are roofers or employees in a fast-food restaurant," Judge said.
For people who had a father who was an economist and mother who was a chemist, for example, the difference is startling. Those who were self-assured made $96,220 a year compared to just $50,968 a year for those lacking in self-assurance.
But for someone whose father was a roofer and mother was a waitress, high levels of self-confidence meant a difference of less than $7,000 a year ($58,117 a year compared with $51,359).
Judge said that the effects of self-esteem and socio-economic background on income are particularly timely with today's growing income disparity between the "haves" and "have nots."
"As our economy becomes more high tech and places a higher premium on knowledge work, it gives tremendous opportunity to people who have advantages based on their upbringing," he said.
"But people who don't have advantages are much more limited in what they can make of themselves, probably because they have so little to capitalize on."
But the study also demonstrates that early advantages by themselves are not enough to guarantee material well-being later in life, Judge argued.
"In light of popular beliefs that kids from middle- and upper-class families have it made, it is surprising to see what little positive impact socioeconomic status has in the absence of self-esteem," he said.
Motivation may be one reason for self-esteem's importance, he added. "Research has shown that positive people who believe in themselves have more ambitious goals, so that even when they encounter adversity, they're not as likely to internalize it."