During a study of the social behavior of capybaras (Hydrochoerus hydrochaeris), our goal was to reliably identify as many animals of all cohorts as possible in a population living in the Venezuelan Llanos. We used lassoing from horseback and 2 drug combinations to capture capybaras in the wild. We tested ear tags, expandable plastic collars, and tattoos as permanent marking techniques. Lassoing was more effective for capturing a large number of animals in a small area, while darting allowed a more selective capture. Ketamine plus N-(3′dimethylaminopropyl)-3-propionyl phenothiazine phosphate (combination A) and ketamine and medetomidine, with atipamezole as the reversal agent (combination B), were effective to immobilize capybaras but did not induce total anesthesia. Combination B was the least convenient because it caused a reduction in swimming ability and therefore a higher risk of drowning than combination A. The only permanent marking method was use of plastic ear tags.