The purpose of this review was to summarize the behavior-analytic literature on the emergence of untrained second language skills and to provide recommendations for future research focused on second language acquisition. Seventeen distinct studies were included in the review. These studies implemented a variety of teaching methods (e.g., tact, intraverbal, mand, and echoic training) and tested for the emergence of untaught verbal operant relations. Results suggest that tact training is an effective approach to evoke untrained responses in a second language, and intraverbal training is effective for training rudimentary second language skills and the emergence of untaught responses. Implications of these findings for research and practice are discussed.