Common teasel (Dipsacus fullonum L.) and cut-leaf teasel (Dipsacus laciniatus L.), from the Old World family Dipsacaceae, are invasive weeds that were most likely introduced into North America in the late 18th century. Since that time, these teasels have spread to 43 states and one or both species are listed as ‘noxious’ in six states and ‘invasive’ in 12 others. Recently they became targets for classical biological control. Survey and host-specificity studies are underway on herbivores and pathogens found on teasels in their native Eurasia. The prospects for successful biological control of these teasels is discussed with regard to the insect herbivores and pathogens identified to date.