Learning to comprehend and produce words is hugely important in human development not only because it helps children learn to communicate, but it subserves several other aspects of development. Fast mapping is a process children use to help determine what a speaker is referring to when presented with a novel word, and children are highly skilled at doing this particularly when a novel object is presented in the context of familiar objects. However, the cognitive processes underlying fast mapping and what role it plays in word learning is poorly understood, making it hard to define. It is assumed that fast mapping leads to word learning, but despite children’s accuracy in fast mapping they tend to demonstrate poor retention of fast mapped words. I will present a number of studies where I have explored the conditions surrounding fast mapping that are associated better retention of multiple novel words and will discuss some of the theories surrounding fast mapping.