This study shows the importance of interaction to student learning within Web-based online learning programs. The population of this study was students enrolled in multiple academic disciplines at a private university in the Washington, DC Metropolitan area. A Web-based research instrument was designed to assess students' characteristics, their perceptions of learning, satisfaction, student-to-student interactions and student-to-instructor interactions. Regression analyses were employed to analyze the relationship of interaction variables with student learning and satisfaction. Student-instructor interaction and student-student interaction were found to be significant contributors of student learning and satisfaction. (Contains 10 tables.)