Police were called shortly after 1:00 p.m. for a harassment complaint at the Willingboro Public Library.
Officers arrived and were told by parents that a man had been following some of the young people around the library and making them feel uncomfortable.
The suspect, 44-year-old Robert Custodio, was found sitting in the Young Adult section of the library. Police say he was viewing inappropriate material on a library computer.
The material was "not suitable for children or young adults," police said.
Custodio was charged with Harassment and Failure to Register under Megan's Law and placed in the Burlington County Jail on $25,000 bail.
Police say the incident is still under investigation.