This study examined how Korean university students, majoring in English interpretation and translation, used their smartphones to meet their language learning needs. We surveyed 241 students on their smartphone use in four conditions: overall use, use related to coursework, use in English related to coursework, and use in English not related to coursework; as well as while engaging in four functional categories: communicating with others, accessing information, Creating and collecting content, and Listening, viewing, and reading. The survey results showed that a majority of participants used English for a variety of activities at least once a day: over 50% used English to communicate with others and to access information daily, over 40% listened to, viewed or read material in English daily, and over 30% created or collected content in English daily. These activities were nearly evenly distributed between activities related to the participants' coursework and more informal activities. We interviewed 28 of the 241 participants to investigate how they used their smartphones to meet their language learning goals. We found that the interviewed participants used their smartphones to create language learning environments, and that these participants took three general approaches to creating their individual language learning environments.