A case study is a detailed study of a learner’s acquisition of an L2.
It is typically longitudinal, involving the collection of samples of
the learner’s speech or writing over a period of time, sometimes
years. The two case studies which we will now examine were both
longitudinal. One is of an adult learner learning English in sur-
roundings where it serves as a means of daily communication and
the other of two children learning English in a classroom.