Ryan T. Mock is in Lehigh County jail in lieu of $250,000 bail for the alleged attack that followed an online meeting, exchange of cell phone numbers and sexting.
Mock is a registered sex offender listed on the Pennsylvania Megan's Law website.
The victim invited Mock to visit her when her parents weren't home, police said.
sexting has become part of adolscent peer pressure. A hit East Penn School District last October.
Social networking sites are involved in 33 percent of Internet-initiated sex crimes, according to Internet Safety 101 and the Journal of Adolescent Health.