In this article we describe an Australian project in which linguists, signed language interpreters, medical and health care professionals, and members of the Deaf community use the technology of the Internet to facilitate cooperative language development. A web-based, interactive multimedia lexicon, an encyclopedic dictionary, and a database of Australian Sign Language (Auslan) are being used to create an effective, accepted, and shared sign language vocabulary for the discussion of medical and mental health issues by deaf clients and health professionals in interactions mediated by Auslan interpreters. The site, called Medical Signbank, is a means of monitoring Auslan vocabulary use and innovation by interpreters and of providing an explanation of basic medical and mental health terminology to deaf people with limited English or literacy skills. Medical Signbank will use the interactive capabilities of the Internet to turn the tables on language planning and standardization—from “top down” to “bottom up”—and, by so doing, encourage an organic and more natural process of language development.