High school seniors about to be admitted to college, take note: that authentic-looking Facebook page inviting you to join the university’s “welcome group” for the class of 2015 may be unauthorized.

A company that calls itself Roomsurf.com, and provides a service for prospective freshmen to find potential roommates for a fee, has created what appear to be official Facebook groups for next fall’s freshman classes at more than 150 colleges, including New York University, Middlebury, Wesleyan, the University of Texas and Pepperdine, according to college administrators, who noted a uniformity among the sites.

Each contains the school’s logo, as well as descriptions like, “Welcome SUNY Oswego Class of 2015” or “Welcome Tufts University Class of 2015.” None of the pages, though, make obvious reference to Roomsurf, or indicate that those who join the group will be sent promotions for the site, which was under construction Tuesday evening. (Its matching services range in price from $4.95 to $9.95, though typically the company has no authority over roommate pairings.)

J. D. Ross, a new media director at Hamilton College in upstate New York, helped trace the sites to Roomsurf  in part through an alias used on Facebook by the Web site’s founder, Justin Gaither. Mr. Ross said the company’s efforts via Facebook constituted “a deceptive marketing tactic.”