This chapter considers the unique opportunities for assessing online collaborative learning (OCL) in both formal (primary, secondary, and tertiary) and non-formal (workplace) education contexts. The chapter provides a theoretical framework, a methodology, and a set of tools for understanding and assessing online collaborative learning and conceptual change. Online collaborative learning (OCL), it is argued, provides hitherto unprecedented qualities for implementing, supporting, and assessing individual and group intellectual progress. The chapter focuses especially on the unique opportunities whereby instructors, educators, researchers, and students can analyze and assess learning (conceptual change) in OCL environments and applications: that is, online discussion that progresses from divergent (brainstorming) to convergent (conclusive statements) in such educational activities as group seminars, discussions, debates, case analyses, and/or team projects. Examples of OCL applications, such as the design of online student-led seminars, and ways to assess student moderators and student discussants, are included.