This chapter focuses on the difficulties of herbicide use on multiple and cross resistant weeds and reviews some weed control techniques that are appropriate to herbicide-resistant weed populations. Successful management of these resistant biotypes can be implemented by using an alternative herbicide to which there is no resistance. In Australia, North America, and many other countries, herbicide technology has facilitated earlier planting of short-season crops and improved weed control in many cropping systems. Unless there is a substantial fitness penalty, resistant biotypes will not be eliminated from a population by selective mortality in the absence of herbicide application within an economically viable period of time. In contrast, only a few of the resistant Avena populations so far described display complex resistance. The introduction of alternative crops into a crop rotation may give the opportunity to change herbicides, to alter the herbicide application rate, or change other weed control techniques.