Source memory represents the origin (source) of information. Recently, we proposed that rats (Rattus norvegicus) remember the source of information. However, an alternative to source memory is the possibility that rats selectively encoded some, but not all, information rather than retrieving an episodic memory. We directly tested this "encoding-failure" hypothesis. Here, we show that rats remember the source of information, under conditions that cannot be attributed to encoding failure. Moreover, source memory lasted at least 7 days but was no longer present 14 days after studying. Our findings suggest that long-lasting source memory may be modeled in nonhumans. Our model should facilitate attempts to elucidate the biological underpinnings of source-memory impairments in human memory disorders such as Alzheimer's disease.