Historically, sulfur (S) application has not been recommended on Iowa soils for corn and soybean production. The soil supply or combination from sources such as manure or precipitation has met crop S needs. However, soil S levels or supply may become depleted with prolonged crop removal, sulfate leaching, low precipitation deposition, and reduced soil organic matter levels. The objectives of this study were to determine if corn and soybean yields would respond to S fertilizer application and rate at sites in central and northeast Iowa.