Two hundred and eighty undergraduates from universities in two countries were asked to read didactic material, and then think and write about potential solutions to an ill-defined problem. The writing was conducted within a synchronous or asynchronous computer-mediated communication (CMC) environment. Asynchronous CMC took the form of email exchanges between American learners only, Southern European learners only, and American and Southern European learners together. Synchronous CMC was restricted to dyads consisting of American-American, Southern European-Southern European, and American-Southern European students dialoguing. Additionally, a number of Americans and Southern Europeans were each paired with a content-"mirroring" computer-generated partner to account of the effect of thinking with an unresponsive partner in synchronous CMC. Results revealed that dyadic learners in asynchronous CMC used significantly more reasoning skills to think about solutions to the problem, while dyadic learners in synchronous CMC exchanged significantly more personal knowledge and features of emotion. However, the tendency among dyadic learners to include emotional features in their dialogues was mediated by their cultural background.