Research related to Web-based learning (WBL) has grown exponentially in the last decade. Scholars have explored a variety of areas related to WBL, including techniques, strategies and best practices. One area of particular interest to scholars is the potential of WBL to support and facilitative collaborative learning. Despite the continued exploration, there continues to be a concern related to the theoretical foundations of WBL. The purpose of this article is to explore how different theories may be used to guide research and inform practice in online collaborative learning. We integrate the major points drawn from current research and theory from a variety of perspectives so as to gain a better understanding of how learning is enabled by asynchronous modes of online collaborative learning. We then use this understanding to identify opportunities and challenges for theory development and research in WBL.