Glyphosate, known by many trade names, including Roundup, is a highly effective herbicide. Widespread glyphosate use for corn and soybean has led to glyphosate resistance, which is now documented in 14 weed species affecting U.S. cropland, and recent surveys suggest that acreage with glyphosate-resistant (GR) weeds is expanding. Data from USDA's Agricultural Resource Management Survey (ARMS), along with the Benchmark Study (conducted independently by plant scientists), are used to address several issues raised by the spread of GR weeds. Choices made by growers that could help manage glyphosate resistance include using glyphosate during fewer years, combining it with one or more alternative herbicides, and, most importantly, not applying glyphosate during consecutive growing seasons. As a result, managing glyphosate resistance is more cost effective than ignoring it, and after about 2 years, the cumulative impact of the returns received is higher when managing instead of ignoring resistance.