Mobile technology melds the mobile learner's authentic real and virtual worlds, enabling increasingly untethered personalized, learner-determined language learning opportunities. This article introduces an evidence-based framework founded upon cumulative findings from a number of the authors' recent and ongoing research projects. This framework provides guidance for designing mobile language learning activities within the learner's evolving personal, authentic situational learning context. The framework consists of three learner dimensions and four external contextual affordances that synergistically define the dynamics of this learning context. The merger of these dimensions and external contextual elements yields three interdependent learning concepts--personalization, adaptation, and relevancy--which enhance the mobile learner's motivation and self-determination. Application of these concepts enables instructors and learners to design mobile language activities that consider the interplay of numerous factors impacting language learning in context. [This paper was presented at WorldCALL 2018.]