This paper reports on a study in which incidental English vocabulary learning from three
mobile modes (book, e-book and e-book with user modelling and adaptive vocabulary
learning support) was investigated. The study employed a crossover design to test for
vocabulary gain from reading three simplified English novels among a group of Japanese
high school students, learning English as a second language. Small vocabulary gains were
noted; however there was no significant difference between the modes in this respect.
Participants also gave their reactions to using the three modes. We reflect on some possible
reasons for the results, and identify some methodological considerations.