The anticholinesterase pesticide carbaryl was injected subcutaneously into rats lever-pressing for liquid reinforcement. During the test session a low intensity footshock accompanied each lever-press response with the carbaryl rats exhibiting a smaller response decrement due to the shock. In the second experiment, carbaryl injected rats displayed a higher behavioral threshold to footshock. These results appear to explain other studies in which animals given anticholinesterase agents show decreased efficiency in performing an avoidance response. Two additional experiments examined the effects of carbaryl on motivation for liquid. Rats lever pressing for liquid reinforcement on an FR-25 schedule were injected with carbaryl. It was found that the response onset after each reinforcement was significantly delayed in the carbaryl animals. This result, in addition to ad lib liquid consumption data, indicated a decreased drive for water in the carbaryl animals. Findings, similar to results obtained using cholinolytics, present an apparent discrepancy which is discussed in terms of (a) the necessity of having an optimum level of Acetylcholine (ACh) in the brain, (b) the possibility of a peripheral mechanism, or (c) the possibility of sympathomimetic effects of carbaryl.