A major problem for large-enrollment, introductory college courses in natural resources and life sciences is poor attendance. To ameliorate this problem, we designed a hybrid course (part online, part face-to-face) to incorporate the advantages of online learning while retaining benefits of face-to-face instruction. We taught a hybrid introductory college science course (containing online assignments) simultaneously with a traditional lecture course (containing passive lectures). Completion rates of online homework were greater than attendance rates to passive lectures, and this difference increased with higher class rank. Our results suggest that hybrid course formats might be effective for increasing student attendance, particularly upperclassmen, in introductory life sciences and natural resource courses. (Contains 3 figures.)