Fifty-one sherds of Terra Sigillata (about 20-0 B.C.) from Arezzo, Italy and Lyons, France have been chemically analyzed by neutron activation and x-ray fluorescence-analysis. The abundances of over elements were measured by neutron activation analysis with an average precision of about 2%. Seven elements were measured by x-ray fluorescence. Cross-comparisons of the two techniques of measurement (and sample preparation) allowed interpretation of the extent to which volatile materials such as carbonate or water influence the results. The sherds from Arezzo formed a homogeneous and distinctive chemical group while all but two of those from Lyons were classified into three such groups. Four additional sherds from houses excavated in Strasbourg and one from Lyons, all of which bear the Ateius signature, have the same composition pattern which closely matched one of those from Montée de La Muette in Lyons. It is therefore suggested that these five sherds bearing the Ateius signature were made in the general vicinity of Lyons and were part of the output of an as yet unknown Gallic branch of the firm of Ateius.