BOSTON -- Assaults, thefts and even x-rated incidents are happening within the walls of Boston's Public Library.

NewsCenter 5's Sean Kelly's reported Thursday that it's a beloved place. Students, researchers, writers and scholars rely on the library's vast collection.

"We're dealing with lots of people. They are coming for hundreds of different reasons," Boston Public Library President Bernard Margolis said.

Most of those reasons are appropriate, but Team Five Investigates obtained incident reports from the two private security companies that protect Boston's libraries.

The reports from 2005 and 2006 document 40 incidents of disorderly behavior including profanity, verbal abuse and vandalism, 15 cases of patrons under the influence, 20 reports of assault, including getting physical with library staff. In one case, a teen pulled a knife on another teen. Most troubling was a number of incidents of sexual misconduct, ranging from pornography to open sexual activity.

"We are vigilant about being sure that our patrons and our staff are safe and secure. It's No. 1," Margolis said. "We'd like to get to zero incidents. I don't think we can. The fact that we are serving a broad spectrum of people."

NewsCenter 5 showed some of the reports to Lisa Barstow of the Massachusetts Family Institute.

"This is a lot more than zero, and certainly unacceptable by anyone's measurement. Would we allow that in a public school? Would we allow that in town hall? We wouldn't allow it," Barstow said.

Team Five found some homeless people using libraries as a refuge. In 2005 and 2006, at least a dozen were cited for sleeping or washing in the bathroom -- both strictly banned under the library's code of conduct, along with other things such as stealing, fighting, harassment or being under the influence.

"The violence, the sexual related incidents, anything involving children, those are typically the issues that are more serious," library security analyst Dick Sem said.

Most of the Boston Public Library system's funding comes from the city and the state. NewsCenter 5 asked Margolis whether he thinks taxpayers are getting the safety they expect in return.

"When people misbehave and are inappropriate under our policies, we will ban them from the library. We do that regularly and without hesitation," Margolis said.

But the incidents that were reported show many banned patrons returned repeatedly but police are not always called. There are more than 20 guards on duty at anytime during business hours, as well as surveillance cameras. Striking the balance between welcoming everyone and keeping patrons safe is a growing challenge.

"Does this sound like enough is being done to keep the library secure?" Kelly asked.

"Certainly not. It's disturbing. Libraries need to be safe place for children and families to learn and go," Barstow said.