Varying levels of chromium, nickel and molybdenum have been made to laboratory heats of stainless steels in order to quantify the effect of these alloying elemente on pitting and crevice corrosion. The nickel level was either 2%, resulting in a ferritic microstructure, alternatively 25% or 40% to give an austenitic steel. The molybdenum level was 2% or 4% and the chromium level 20 or 25%. Critical temperatures for pitting corrosion or crevice corrosion have been evaluated in 1M NaCl and 0.2 or 0.05M NaBr. Results are evaluated in using multiple linear regression to obtain modified Pitting Resistance Equivalent equations relating corrosion performance to alloy content. Electrochemical studies have also been used to elucidate the component propagation and repassivation processes.