The multi-variable locomotor activity effects of LiCl treatment in female rats were examined in a conditioned place avoidance/aversion (CPA) paradigm. In addition, the sickness effects of an LPS injection (200μg/kg), given during adolescents, on CPA learning in adulthood were examined, as were the effects of a homotypic LPS injection (200μg/kg) just prior to CPA acquisition trials. Female rats were injected with LPS or saline during adolescents (6 weeks of age) and later pretreated with LPS again or saline in an automated two-chamber CPA paradigm with LiCl (95mg/kg) treatments as the aversive toxin. Results showed that, while adolescent LPS treatment had no long-term effect on the establishment of CPA, it did interfere with the ability of a second LPS challenge in adulthood to impair CPA learning, an effect obtained in subjects pretreated with LPS in the CPA procedure in adulthood only. The results of this study demonstrate the importance of considering the adolescent stage of development when evaluating the effects of environmental challenges on adult behavior.