For the past decade the provincial drug plan in British Columbia has based the allocation of public subsidy on scientific standards of evidence. Coverage policies under B.C. PharmaCare are marked by the restriction of public subsidy until manufacturers provide valid evidence of a comparative health outcome advantage versus therapeutic alternatives. Implementing and maintaining such outcomes-based coverage policies has required a system of evidentiary review and support. Since 1994 the Therapeutics Initiative at the University of British Columbia has provided provincial decisionmakers with such support. We describe lessons from the B.C. experience for jurisdictions interested in basing coverage on evidence of proven comparative advantage for patients' health.