Critical to maximizing the potential of technology for learning is enhancing language learners' self-directed use of technology for learning purposes. This study aimed to enhance our understanding of the determinants of self-directed technology use through the construction of a structural equation modelling (SEM) framework of factors and interactions that determine students' self-directed use of technology for language learning. A survey was conducted among second language learners at one university in Hong Kong to provide the basis for a model that describes how various psychological and sociocultural factors interact to influence language learners' use of technology for learning outside school. Attitudinal factors--such as "language learning motivation," "perceived usefulness of technology for learning," and "perceived compatibility between technology use and learning expectancies"--played a dominant role in shaping technology use. Perceived support from teachers and peers, self-regulation skills, and confidence in the selection and use of technology effectively impacted technology use mainly through strengthening perceived compatibility and usefulness. The findings suggest that attitudinal factors deserve much greater attention than currently given in promoting language learners' self-directed use of technology.