Many people want to learn a foreign language, but issues of time, convenience and cost mean that classes are often insufficient for learners, and increasingly learners are supplementing or replacing their classroom learning with online learning. The majority of existing online language learning systems use the traditional grammar-translation approach (i.e. a focus on grammar and translation skills) to language learning. This approach has inherent scale limitations because learning materials must be carefully designed by experts, often requires that learners engage with topics that are irrelevant to their goals and interests, and lacks contextual information that is important for language skill. However, drawing from communicative language approaches (i.e. approaches that focus on meaning rather than correctness, and assess learners based on the activities that they can engage in rather than their knowledge of rules and vocabulary), we can reimagine the design of online language learning to overcome these challenges. Through discussion of three projects, I show that by leveraging readily available native-speaker media, automation, and communicative-learning approaches, we can use (i) learner activity from even novice learners to annotate learning materials (e.g. captions and phonetic readings), (ii) freely available videos and speech recognition to enable contextualized learning practice, and (iii) videos and captions to generate automated learning assessments that capture general proficiency rather than specific vocabulary and grammar knowledge. This work makes contributions in areas of design, language education, language research methodology, and language learning theory. In design, this work shows how we can build effective language learning experiences around existing materials. In language education, this work generated new learning systems which have been used by independent learners and in classrooms. In language research methodology, this work contributes a new way for researchers to assess learner proficiency using a quick test generated from existing materials. Finally, in language learning theory, this work shows a paradigm shift from the grammar-translation approach to a communicative approach in language system design. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]