In a previous issue of this Journal, MacWhinney & Snow (1985) laid out the basic sketch for an international system for exchanging and analysing child language transcript data. This system--the Child Language Data Exchange System (CHILDES)--has developed three major tools for child language research: (1) the CHILDES database of transcripts, (2) the CHAT system for transcribing and coding data, and (3) the CLAN programs for analysing CHAT files. Here we sketch out the current shape of these three major tools and the organizational form of the CHILDES system. A forthcoming book (MacWhinney, in press) documents these tools in detail.