Severe parasite infections in beef cattle are sometimes associated with decreased growth and performance and clinical disease. Stocker cattle are exposed to many parasites and appropriate deworming strategies can help to minimize parasite burdens when cattle are on grass. Feedlot cattle are often dewormed at arrival and have minimal exposure to additional parasites once placed in the feedlot. The purpose of this study was to evaluate stocker and feedlot performance and carcass characteristics relative to treatment with deworming agents of varying durations of activity.