Integrating research on both linguistic and semiotic resources of translanguaging practices, this research was carried out using a case study design to understand how translanguaging was used by both ESL teachers and adult language learners in the ESL setting, what functions translanguaging performs, and how teachers and students understand their translanguaging practice. Nine adult ESL learners at the intermediate level and an ESL teacher participated in this research. Data sources included observations, interviews, field notes, and reflective journals. Discourse analysis was used to analyze the transcription of observations and interviews. Results showed that participants used various forms of translanguaging, including gestures, L1s, facial expressions, English songs, etc. Translanguaging performed seven functions in this language class: (a) to substitute words or phrases that someone forgets or does not know, (b) to facilitate understanding by supporting the oral presentation, (c) to add new meanings by supplementing the oral presentation, (d) to ease anxiety, (e) to show understanding or clarify misunderstanding, (f) to make associations between languages, and (g) to acknowledge others as multilinguals. In addition, interviews showed that most participants held a relatively positive attitude toward translanguaging, with slightly various thoughts and ideas. Practical and research implications were also discussed. [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.]