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In previous work, we showed that adult rats that were reared socially for 3 months in a complex (village) environment retained allocentric spatial memory for that environment following hippocampal lesions (Winocur et al.,(2005) Nat Neurosci 8: 273–275). In the present series of experiments, we showed that 3 months of postoperative rearing did not confer the same benefits (Experiment 1), although hippocampal groups, with or without rearing experience, exhibited spatial learning after extensive training (Experiments 1 and 2). Experiment 3 showed that as little as 2 weeks of preoperative rearing in the village was sufficient to retain acquired spatial memories after hippocampal lesions. Probe testing revealed that, although rats with hippocampal lesions exhibited remarkably good memory for preoperatively learned locations in the village, they were impaired when changes in task demands required flexible use of …