Previous research has provided evidence that mental imagery and embodied action can facilitate lexical learning in a novel language. However, it is unclear "how" these factors interact--as well as "why" they play a role--in lexical learning. Through a set of four experiments, this research demonstrated that neither mental imagery nor embodied action directly promotes the acquisition of second language (L2) words. The results of a fifth experiment provide evidence that both mental imagery and embodied action enhance ASL sign acquisition through enactment. Taken together, these results indicate that the body plays a more pivotal role in the early stages of sign acquisition than it does in the early stages of spoken L2 word learning. Overall, the results provide some support for embodied theories of language acquisition and processing and indicate that the saliency of perceptual experiences underlying lexical items and their referents depends on modality of communication. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]