Goodness, now I don't remember when I read this. It had to have been a few weeks ago or so, maybe longer. I don't know. I had to read it for my Applied Linguistics course. It provides an overview of the predominant second language learning theories, including the linguistic approach, cognitive approach, socioloinguistic approach, and the functional/pragmatic approach. Of the theories discussed in here, most important is the linguistic theory that arises out of the linguistic approach, and which all the other approaches seem to have to be dependent upon to be even coherent. Linguistic theory posits that human beings have an innate cognitive capacity for language reception and production that operates according to fixed principles and which changes relative to specific languages by modifications of certain innate parameter switches. Also interesting is research done in information processing theory in the cognitive approach, which seeks to understand language at the level of the brain. For social or situations purposes, the research of Dell Hymes et al. that arose out of the functional/pragmatic approach is also important. These are of course my preferences for what I think is the fruitful research.