We review a body of behavioral and neuroimaging research relating to the acquisition and integration of novel words. An important outcome from this research is that different aspects of knowledge associated with learning a new word become established over different time scales. We suggest that the temporal dissociations found in word learning are due to the application of and interaction between complementary learning systems in the brain, with rapidly acquired episodic representations stored via the medial temporal lobes and slower learning supported by neocortical systems. We discuss the implications of this model for understanding the earliest stages of learning a novel word and for learning words in a second language.