This report describes an operant conditioning technique for studying crocodilians. As experimental subjects, crocodilians present some special problems. For example, their size limits direct handling. Further, because they may go for prolonged periods without eating, food probably is not an effective reinforcer. And, because of the crocodilian's limited overt activity, obtaining a specified response can be very difficult; much of the time crocodilians seldom move. In addition, their ability to manipulate objects is limited by their morphology. Therefore, responses (e.g., barpresses) and procedures (e.g., shaping) typically used in such experiments are not practical. Weiss and Laties (1961) demonstrated behavioral thermoregulation in the rat by having the animals press a bar to activate a heat lamp. Crocodilians are cold blooded, so it was assumed that heat might serve as a reinforcing stimulus and that crocodilians would demonstrate behavioral thermoregulation. Because it appeared to be difficult for the reptile to move its head forward to depress a key (as pigeons do), the behavior to be conditioned was simply making contact with a metal plate.