Potato growers continue to rely on neonicotinoid insecticides, primarily imidacloprid and thiamethoxam, for Colorado potato beetle (Leptinotarsa decemlineata) control. While neonicotinoids remain highly effective, the consistent use of one class of insecticide further increases the risk of resistance development. Populations from across the United States were bioassayed for imidacloprid and thiamethoxam resistance in 2006. In addition, an intensive monitoring effort was conducted at a farm in central Michigan where beetles have shown high levels of imidacloprid resistance in previous years. Nationwide, resistance values were consistent with previous years, with high levels of resistance along the East Coast and susceptible populations in the Midwest. The Michigan farm was the noted exception. Beetles from several fields on this farm were greater than 10 fold resistant to imidacloprid compared to susceptible beetles. Resistance to imidacloprid is highly correlated with resistance to thiamethoxam, although resistance to thiamethoxam remains at a lower level than resistance to imidacloprid. Monitoring of resistance and cross resistance is a critical part of resistance management.