— This paper presents a study of the learning process in a distance collaborative learning environment with a chat system and a Wiki, and development of a new chat system based on the study. Collaborative learning as the combination of conversation and collaborative work was investigated, which revealed 1) There is a time lag between conversation and work, 2) Awareness of other learners is problematic in distance collaborative learning. Based on the investigation, an activityaware chat system that indicates both conversation and work has been developed. Keywords-CSCL; activity awareness; chat; behavior analysis