While the professional networking site LinkedIn is now regarded as the second most-popular social networking site in the U.S., Facebook still stands strong at number one, with over 160 million users. Your Facebook profile can play an important role in your professional life, whether or not you realize it.And the first thing people see on Facebook—before they read about your dual degree or favorite rom-coms—is your profile picture. If you’re in the market for a job, it’s a no-brainer that you shouldn’t showcase your rowdy margarita night. But what about a more conservative pic with a group of your friends? Maybe not.MORE: Boss Troubles? Take Control for Less StressEmployers don’t necessarily want to know how friendly you are. In a not-yet-released Facebook study, subjects posing as potential employers rated solo profile pics and a low number of Facebook friends more favorably than profiles with a group photo and high number of Facebook friends. So in terms of showing your social network, bigger isn’t always better.“This could be because those with a high number of friends were rated as more extroverted and less conscientious, which would be undesirable in the workplace if you spend most of your time socializing,” says lead author Debra Elise Stewart. So how much is too much? Definitely anything over 600 friends, the study suggests.Ideally, if you have good traits that are desirable to your job position, you shouldn’t have to hide your online profile. A study from Psychological Science found that people’s real-life personalities typically translate onto Facebook. Generally, observers accurately rated the personality traits of Facebook users, particularly extroverted people (perhaps because they share more info, so there’s more to judge).So, keep your profile as is?You could, “if you knew that you were responsible and competent and that came across in your profile…but we’re not in a good position to judge that about ourselves,” says study co-author and Assistant Professor of Psychology, Simine Vazire, Ph.D.So to be safe, you might not want to have a profile when you’re job searching. Even if you think you know what your potential employer wants, “you can’t change your profile overnight to fit what they’re looking for,” Dr. Vazire adds.Not to mention, companies like Social Intelligence Corp. perform extensive online searches for Human Resources departments, tracking your activity on Facebook, Twitter, YouTube, LinkedIn and blogs. The federal government recently gave this company the OK to dig for some serious online dirt.If you’re 100-percent sure you’re squeaky clean, just take some of these steps to have better control of your online profile image…Go to your Facebook privacy settings and choose that only you can see “Photos and videos you’re tagged in.” Everyone has one friend who likes to snap away and post pics from every party. The pic may be on other people’s profiles, so untag yourself if you don’t want your name linked with your photo.And when you’re wary of making an edgy comment on the web, do the tried-and-true test: Would you mind if the whole world (wide web) knew it?