As Gene McHam sat at a foldout desk in McCormick 101 yesterday morning, he listened attentively to Professor Angela Gleason's HIS 343: Civilization in the Early Middle Ages lecture.
Though he might seem like a typical student, McHam's silver-gray hair sets him apart from the crowd. His age also sets him apart; he is 72.
McHam was accepted to the University in 1953 but was unable to attend for financial reasons. Now a local resident, he is one of about 650 alumni, University community members and local residents in the Community Auditing Program (CAP), which allows them to audit classes for $120 per course per semester.
Many CAP participants, like McHam, are retired and see the program as an opportunity to continue learning though their official school days are long gone. "It's changed my life — I think very differently now," he said. "I've taken nine or 10 philosophy courses. They're amazing."
As she was leaving a lecture for MOL 214: Introduction to Cellular and Molecular Biology, a course she co-teaches, President Tilghman said CAP is "a way [the University] can provide public good."
The program "elicits a great deal of good from the community and shows the intellectual breadth of the community," but it does so in "a way that does not hinder the education of students," she said, citing the rule that only 10 percent of a course's enrollment can be community auditors.
Though the class was filled with premeds hurriedly scribbling notes, a few auditors sat in the back of the class, listening to Tilghman's lecture on Drosophila development and absorbing her lecture without the worries of grades, exams and graduate school.
Created in 1998, CAP "started on a much smaller scale," Director of Community and Regional Affairs Kristin Appelget said. "It was a formalization of something that had been occurring for a number of years."
McHam said he remembers instances before the creation of CAP when less formal rules for community auditing resulted in crowded classrooms where auditors threatened to disrupt classroom dynamics. "There was a time a few years ago when there were so many auditors that they were overwhelming the undergraduates," he said.
The University has solved this problem through closely regulating enrollment and increasing the course fee, he said.
Appelget said that the program's enrollment rose dramatically last spring with the creation of an online application for community auditors. "I know from our current standpoint that our participants respect the fully enrolled students they take classes with," she said.
Auditors are expected to refrain from commenting during lectures, but that has not stopped them from befriending and mentoring students, Appelget said. "Quite a few of our auditors have been high-level executives, doctors and lawyers," she added. "Sometimes professors have drawn auditors into the conversation."

Economics professor Elizabeth Bogan said that the real-world experiences of auditors in her ECO 101: Introduction to Macroeconomics course have enhanced her lectures. "When I [make] historical comments," she said, "it's helpful to have some of these guys come in and confirm them."
Course availability to auditors is based on the consent of professors, and openings are filled by online registration on a first come, first served basis. Courses across the University's academic departments are open to auditing.
"I've taken courses in astrophysics, Chinese history, the western way of war, women's rights [and] economics," said Arthur Fein, who is auditing the molecular biology course guest-lectured by Tilghman.
Appelget said courses in English, politics and art history are generally the most popular with community auditors.
CAP offers two yearly lecture series exclusively for auditors over four consecutive Fridays in March and April. This year, course topics range from opera to international politics. Alumni auditors are given preference for courses, as well as the exclusive offerings, by receiving the opportunity to register early, Appleget said.
McHam said the process can be more of a hassle for community members unaffiliated with the University. "The registration process is a stampede, as you can imagine," he said. "You must prove you are a [Princeton] Township or Borough member."
In May, CAP will hold a closing ceremony to conclude the semester with a guest lecture by English professor Jeff Nunokawa, an especially popular professor among auditors in the program.