It’s common now for workers to change jobs every three or four years. But leaving companies after a year or two of employment is still seen as a liability.

Perfectly qualified candidates often don’t make it through the initial résumé-screening phase due to histories of job-hopping, says Louise Kursmark, author of “Sales & Marketing Résumés for $100,000 Careers” (Jist Publishing, 2009), now in its third edition.

Changing jobs too frequently “suggests you either weren’t very good at your job, you can’t hold a job, you’re unstable or you’re the first to be let go when something happens,” says Kursmark, who lives in Boston.

Forty percent of the recruiters, hiring managers and human resources professionals interviewed for Kursmark’s book listed job-hopping as a reason for immediately discarding a résumé.

But some recruiters are more forgiving, in part because of the recession.

“Jobs in short succession are not a red flag in itself – not in this day and age,” says Cathleen Faerber, a recruiter with the executive search firm The Wellesley Group in Buffalo Grove, Ill. “Companies downsize, relocate, merge, etc. Jobs are affected. However, candidates need to have a plausible and verifiable reason for changing each position.”

Disliking a supervisor or office policies are not seen as valid reasons, as they reveal a pattern of disgruntlement, Faerber says.

There are definitely circumstances where a move within two years makes sense. “For instance, if you’re offered a dream job or a huge increase in title and compensation,” says Kurt Weyerhauser, a recruiter with the Irving, Calif.-based executive search firm Kensington Stone Associates. “Such circumstances are no-brainers. However, it would be wise for people to see three years as a minimum threshold to avoid scrutiny.”

Multiple one- or two-year stints will raise eyebrows, he adds. That’s because companies invest a significant amount of time and money training employees and want a return on investment.

Workers with a history of job-hopping can downplay it on their résumés to improve their chances of landing an interview, Kursmark says.

While job seekers should never omit dates, they can organize and format their résumés so the dates “aren’t the first thing that hits people over the head,” she says.

Instead of a chronological résumé, candidates can use a functional résumé, grouping work experience by skill or job function. They can design their résumés in such a way that dates aren’t set off by themselves.

Candidates can eliminate one or more of their jobs, provided that doing so does not leave a gap that employers will immediately question. If the omitted jobs come up later in an interview, “It’s perfectly legitimate to explain that you only had two pieces of paper and wanted to include the most relevant positions,” Kursmark says.

If compelling reasons or circumstances beyond an employee’s control caused a series of short tenures, he or she can add a brief explanation for the departures. “If the company went bankrupt or a merger eliminated your position or you were recruited away, those are reasons that might eliminate an employer’s concerns,” Kursmark says.

“Generally, I advise against excusing or qualifying on a résumé,” she adds, “but sometimes brief statements are called for to overcome a negative reaction.”

Job seekers should concentrate on finding opportunities through networking, because personal referrals can get them in the door.

Then, “You could emphasize that up until now you have been looking for opportunities to expand your skill set but now you are looking for an opportunity to work on a long-term basis for an employer who will use those skills to your mutual advantage,” says business consultant Robert Fallis, Seattle.

Interviewees need to be prepared to explain why they left every job.

“Explain the circumstances in a way that moves the conversation forward,” Kursmark says. “Your answer should be geared to what you accomplished while you were there, and then you can connect that to what you can offer the employer and get the conversation back on track.”

Provided there’s no pattern of poor decision-making, “It’s not inappropriate for someone to very sincerely explain that they made a wrong move,” Faerber says.

Finally, when offered a job, candidates should be as certain as possible that the position is a stable one that they’ll hold for several years so they don’t face the same job-search challenges in the near future.