Colorado residents age 55 and over can sit in on classes at the University of Colorado at Boulder without paying tuition through a longstanding program that will be available during the upcoming fall and spring semesters. Senior Auditors, created by the CU Board of Regents in 1973, enables nontraditional students to attend most regularly scheduled daytime classes without paying tuition. Participants will not receive academic credit for courses they audit, however, and the program excludes Spanish, Portuguese and Continuing Education classes.