Washington Arbitration Services, the predecessor to WAMS, was established in Seattle by attorney Michael S. Gillie in 1981. Mr. Gillie's objective in establishing WAMS was to provide an alternative settlement forum for litigants involved in traditional cases, such as automobile accident and consumer claims. Gillie found some initial success with consumer claims resolution programs he established for the Washington Attorney General's office, but in other areas of the law, so-called "alternative dispute resolution" was still not widely accepted. In 1985, Gillie and Seattle attorney Alan Alhadeff agreed to work together to develop a mediation training and marketing program for insurance claims. Their objective was to provide insurance companies and plaintiffs' attorneys with an inexpensive and accessible alternative to trial: mediation.

In the early 1980s, Gillie developed a claims resolution pilot program for Travelers Insurance. Travelers agreed to refer claim files into mediation on an experimental basis and track the overall settlement and transaction costs versus litigation. In conjunction with the Travelers project, Gillie expanded the business model used to establish WAMS by franchising ADR businesses throughout the U.S., Europe and Canada under the names of U.S. Arbitration & Mediation, Inc. (USAM) and International Dispute Resolution, Ltd. (IDR).