This article presents a joint discussion given at the 1964 AWWA Annual Conference in Toronto, Ontario, Canada. Paper topics and their authors include: Progress in Certification, by George W. Burke Jr., U.S. Public Health Service (USPHS), Division of Water Supply and Pollution Control, Washington, D.C.; Model Mandatory Certification Plan, by John E.Vogt, Michigan State Department of Health, Lansing, Michigan; Mandatory Licensing in New Jersey, by Samuel D. Faust, Rutgers State University, New Brunswick, New Jersey, and by John Wilford, New Jersey State Department of Health, Trenton, New Jersey; and, Voluntary Certification in Florida, by David B. Lepe, Bureau of Sanitary Engineering, Florida State Board of Health, Jacksonville, Florida.