This paper describes a new approach to mobile language learning; a mobile reader that aids learners in extending the breadth of their existing vocabulary knowledge. The FLAX Reader supports L2 (second language) learners in English by building a personalized learner model of receptive vocabulary acquisition. It provides dictionary lookup for words that they struggle with, tracks a learner's reading speed, and models their vocabulary acquisition, generat-ing appropriate exercises to aid in a learner’s personal language growth.