In the last year, the number of colleges offering their students online music through legal arrangements with various providers has more than tripled, to 70, according to a report submitted to Congress Wednesday.

Those colleges enroll more than 670,000 students -- and many other institutions are expected to join the list soon. The idea of offering these deals, pioneered at Pennsylvania State University, is to pay a flat sum for unlimited online music. The motivation is simple: Colleges are tired of being caught in the middle as the music industry tries to crack down on students who engage in illegal file sharing, frequently involving college networks.

The report on how colleges are responding was prepared by the Joint Committee of the Higher Education and Entertainment Communities, which is led by Graham Spanier, president of Penn State, and Cary Sherman, president of the Recording Industry Association of America.

When Spanier first floated the idea of having colleges obtain online music for students, many were skeptical. But the colleges that have embraced the idea are all over the country and include many large and/or prestigious institutions. (A map on Penn State's Web site lists all of the institutions with such policies.)

While the report praised this approach, it also noted that it has limits. Some students at colleges with free legal music services still prefer to download music themselves. And as the report noted, since students don't boast about such activity (at least not to university administrators), it is not always easy to know how successful colleges have been at minimizing illegal file sharing.

Colleges have the most success of offering a music service, the report said, if they first crack down on illegal file sharing, and enforce policies against copyright violations. The report outlined a number of tools being used by colleges to block students from engaging in illegal file sharing. The University of Florida, for example, has created a company called Red Lambda to market a device to stop file sharing.

The report also warned that even as colleges crack down on illegal file sharing, students come up with new ways to do it. One recent trend is for students to use portions of universities' Internet2 network for file sharing, the report said.