The change in color of artists' oil paints caused by the vehicle was determined by normal aging and by an accelerated method. Two cycles causing yellowing followed by exposure to normal room illumination were conducted. Color is reported by the ASTM D 1925 Yellowness Index. Tested were linseed and safflower oils and alkyd, damar, and copal resins. Safflower oil and medium-oil-length alkyds yellowed the least. If linseed oil is predominant, the rest of the vehicle has little effect. -- AATA