In 1991 over 38% of all U.S. college students, and nearly 42% of female U.S. college students, were age 25 or older. According to projections, by 1998 the number of nontraditional (age 25 or older) U.S. college students will rise to almost 46% (U.S. Bureau of the Census, 1995, p. 178-179). The Education Resources Institute (1996) reported that the percentage of college students age 40 or over grew from 5.5% of the total enrollment in 1970 to 11.2% in 1993, making this group the fastest-growing age category during that period. Clearly, nontraditional students will continue to be an increasingly significant part of the college classroom. Despite their significance, nontraditional college students have been largely ignored in investigations of classroom discussion. Much of the debate has centered around the issue of student gender in the college classroom with little consideration to the impact of student age on classroom participation. The Education Resources Institute (1996) report described the typical 40 and over student as a white female who attends a community college part-time and works thirty or more hours per week. Thus, as Howard, Short, and Clark (1996) suggested, due to their different life experiences, nontraditional students' definition of the situation in the college classroom is likely to differ considerably from that of traditional students. These differences contribute to the greater willingness of nontraditional students to participate in classroom discussion. Because Howard, Short, and Clark's (1996) sample of 13 introductory level courses were taught almost exclusively (12 of 13 courses) by female instructors, it was not possible to consider the effect of instructor gender or course level in the mixed-age classroom. This study seeks to fill that void in the literature and contribute to the ongoing debate regarding the impact of student age, student gender, instructor gender, and course level on student participation. Previous Research Since Hall and Sandler's (1982) contention that the college classroom presents a chilly climate for female student participation, the issue of student gender has been the object of considerable study with ambiguous results. Several studies found no effect of student gender (Boersma, Gay, Jones, Morrison, & Remick, 1981; Cornelius, Gray, & Constantinople, 1990; Crawford & MacLeod, 1990 [in their university sample]; Hamlin & Janssen, 1981). However, other studies have concluded that males participate disproportionately (Brooks, 1982; Constantinople, Cornelius, & Gray, 1988; Crawford & MacLeod, 1990 [in their small college sample]; Fassinger, 1995; French, 1984; Graddol & Swann, 1989; Karp & Yoels, 1976; Pearson & West, 1991; Spender, 1981). Brooks (1982) linked males' greater levels of participation with instructor gender, suggesting that males participate more than females in female-taught classes. On the other hand, Sternglanz and Lyberger-Ficek (1977) and Pearson and West (1991) concluded that male students are more likely to dominate discussion in male-taught classes. Auster and MacRone (1994) found that instructor gender was not a significant determinant of student participation. Fassinger (1995) concluded that although instructor gender had no effect on the participation of male students, female students were more likely to participate in classes taught by female instructors. Class size was found to be a significant determinant of participation in classroom discussion in several studies (Constantinople, Cornelius, & Gray, 1988; Crawford & MacLeod, 1990; Fassinger, 1995; Howard, Short, & Clark, 1996). Fassinger (1995) emphasized the role of student traits (e.g., confidence, comprehension, interest, and preparation) and class traits (size, emotional climate, interaction norms, frequent large group discussions) over instructor traits (e.g., gender). Nunn (1996) challenged Fassinger's (1995) findings by concluding that the instructor's choice of teaching techniques (e. …