Interaction in online learning (OL) has been extensively studied over the past few decades. Today, courses following social constructivist (Vygotsky, 1997) based designs are widespread throughout higher education. These course designs place an emphasis on interpersonal interaction, which is largely viewed as beneficial to online learners, as a means to decrease transactional distance (Moore, 1993). Conversely, alternative course designs that emphasize student-content interaction more than interpersonal interaction, as proposed by Anderson's (2003) interaction equivalency theory, present attractive alternatives for educators seeking to cut costs and increase their flexibility of offerings. Purposeful interpersonal interaction (PII) is defined as any high quality, organic, and valid communication exchanges between two or more participants of the learning process that directly relate to the achievement of established learning outcomes or to the building of social relationships. This study attempted to shed insight on how purposeful interpersonal interaction (PII) impacts student satisfaction and perceived learning in asynchronous OL environments by comparing courses in two graduate programs at Carlow University in Pittsburgh, Pennsylvania. Results demonstrated that greater PII does generally lead to greater student satisfaction and perceived learning. A comparison of the two programs also revealed that comparable levels of student satisfaction and perceived learning can be achieved despite lesser levels of PII, giving evidence of a point of diminishing returns for interpersonal interaction. The results generally give further support for social constructivist-based course designs. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]