The Austronesian comparative dictionary (ACD) is an open-access online resource that currently (June 2013) includes 4,837 sets of reconstructions for nine hierarchically ordered protolanguages. Of these, 3,805 sets consist of single bases, and the remaining 1,032 sets contain 1,032 bases plus 1,781 derivatives, including affixed forms, reduplications, and compounds. Historical inferences are based on material drawn from more than 700 attested languages, some of which are cited only sparingly, while others appear in over 1,500 entries. In addition to its main features, the ACD contains supplementary sections on widely distributed loanwords that could potentially lead to erroneous protoforms, submorphemic “roots,” and “noise” (in the information-theoretic sense of random lexical similarity that arises from historically independent processes). Although the matter is difficult to judge, the ACD, which prints out to somewhat over 3,000 single-spaced pages, now appears to be about half complete.