The purpose of this study was to contribute to a better understanding of learning in computer-supported collaborative learning (CSCL) environments by investigating the co-occurrence of uncertainty expressions and expressions of learning in a graduate course in which students collaborated in classroom computer-mediated discussions. Results showed that uncertainty expressions appeared related to the kinds of intellectual work engaged by students in online discussion, co-occurring with learning in systematic ways. For example, direct expressions of uncertainty were likely to co-occur with learning categories associated with presenting a new idea and with applications of an idea whereas indirect expressions were more strongly associated with elaborating on a new idea. These findings suggest that the ability to deal with and express uncertainty appropriately may be related to learning as it takes place in online environments. We contend that the role of uncertainty in learning is currently undervalued, and that educators and researchers may benefit from considering how uncertainty can be productive for learning in CSCL environments.