Abstract: Transgenic plants expressing Bacillus thuringiensis (Bt) insecticidal crystal (Cry) proteins represent a relatively novel method for insect control. This insect control technology is commercially available in corn, cotton and soybean. The continued success of these Bt crops depends to a large extent on the potential development of resistance in insect populations. Insect resistance management (IRM) strategies have been implemented proactively in an effort to delay such resistance build-up. Examples are provided of successes and challenges in IRM for Bt crops.