A total of 38 types of stainless steel have been exposed for 1 to 15 years at a coastal site and 32 years in a semirural atmosphere. The resistance of stainless steels to degradation in the atmosphere was directly related to alloy chromium and molybdenum contents. Only American Iron and Steel Institute (AISI) Type 410 showed any signs of corrosion in the semirural environment. Significant corrosion product tarnishing occurred on all nonmolybdenum-bearing stainless grades after only one year of exposure in the marine atmosphere. Stainless grades that had been sensitized by an autogenous welding operation were susceptible to preferential corrosion at weld and heat-affected zone surfaces when exposed at the 250-m lot on Kure Beach, NC. Galvanic attack and corrosion product staining was observed for certain dissimilar metal couples between AISI Type 304 and other commercially pure metals, nickel-base and copper-base alloys. A photometric technique was used to quantitatively describe subtle changes in the appearance of three stainless steel surface finishes during exposure in a semirural atmosphere.