FORTUNE — So you’ve worked hard, produced great results, and have all the right qualifications. Nevertheless, that bigger job you had your eye on went to your boss’s golf buddy, or old college roommate, or brother-in-law instead.

Scant consolation though it may be, but you’ve got plenty of company. A whopping 92% of senior executives say they have seen favoritism — defined as the use of criteria other than performance — determine who gets promoted, says a new study conducted by consultants Penn Schoen Berland on behalf of Georgetown University’s McDonough School of Business.

While 84% of the executives surveyed reported they had witnessed favoritism at their own companies, only 23% admitted that they themselves have ever relied on friendship or other personal affinity, rather than merit, in their promotion decisions.

The research also notes how common it is for managers to know in advance who will be promoted, even when they go through the motions of considering several candidates.

Almost one-third (29%) of those polled said they considered only one person and, when more than one was in the running (or at least appeared to be), 56% said they already knew at the outset whom they wanted to promote. “Of that group, nearly all — 96% — reported promoting the pre-selected individual,” the study says.

Even so, when the same survey asked executives to give their reasons for recent promotions, most mentioned objective criteria such as “has excelled in current position,” “job-related skills,” and “history of strong performance reviews.”

That means, says study author Jonathan Gardner, that “despite widespread favoritism,” employees who want to move up should “continue to focus their efforts on these factors that are well within their control.”

What comes through loud and clear, however, is that cultivating friends in high places couldn’t hurt either. Golf, anyone?