The past and current EPA research and regulatory programs as they relate to non-regulated emissions from light-duty motor vehicles are reviewed. Provisions of Sections 202(a) and 211 of the 1970 Clean Air Act Amendments are discussed and their relationships to the nonregulated emissions issue detailed. The EPA position regarding non-regulated emissions from oxidation catalyst-equipped vehicles is discussed and related to technical papers presented in this symposium. The planned EPA research programs addressing the "catalyst" issue are reviewed.