More than one in five employers search social networking sites to screen job candidates, according to a survey of more than 31,000 employers released by CareerBuilder.com this week.

Of the hiring managers who use social networks, one-third said they found information on such sites that caused them to toss the candidate out of consideration for a job, the survey said.

The study found that the number of hiring managers that are turning to social networks like MySpace and Facebook to delve into candidates' online behavior is increasing quickly: Some 22% of employers said they already peruse social networks to screen candidates, while an additional 9% said they are planning to do so. Only 11% of managers used the technology in 2006.

The top areas of concern found on social networking sites include:

• Information about alcohol or drug use (41% of managers said this was a top concern)
• Inappropriate photos or information posted on a candidate's page (40%)
• Poor communication skills (29%)
• Bad-mouthing of former employers or fellow employees (28%)
• Inaccurate qualifications (27%)
• Unprofessional screen names (22%)
• Notes showing links to criminal behavior (21%)
• Confidential information about past employers (19%)

The study did find that 24% of hiring managers found content on social networks that helped convince them to hire a candidate. Hiring managers said that profiles showing a professional image and solid references can boost a candidate's chances for a job.

"Hiring managers are using the Internet to get a more well-rounded view of job candidates in terms of their skills, accomplishments and overall fit within the company," said Rosemary Haefner, vice president of human resources at CareerBuilder.com, in a statement. "As a result, more job seekers are taking action to make their social networking profiles employer-friendly. Sixteen percent of workers who have social networking pages said they modified the content on their profile to convey a more professional image to potential employers."

CareerBuilder recommends that job seekers:

• Remove pictures, content and links that can send the wrong message to potential employers.
• Update social networking profiles regularly to highlight latest accomplishments.
• Consider blocking comments to avoid questionable posts; avoid joining groups whose names could turn off potential employers.
• Consider setting profile to private so only designated friends can view it.