The first chapter provided an introduction to the way in which people began to rethink common attitudes to second language learning. Another way of getting a realistic feel for the kind of thinking that guides second language research is to look at methods and techniques used in actual investigations. The discussion here will deal with some of the practical and theoretical problems that arise when actually collecting and analysing IL data. General questions of experimental design and statistics should be gleaned from appropriate books (e.g. Hatch and Farhady 1982, Butler 1985, Seliger and Shohamy 1989, Hatch and Lazaraton 1991).