This document discusses several models of second language learning that consider individual differences and other variables. It examines models that focus on independent learner variables like the Good Language Learner Model, Monitor Theory, and frameworks from Brown & Fraser and Levin. It also looks at models incorporating individual differences like Gardner's educational model, Skehan's model of influences, and Spolsky's model of second language learning. The document provides an overview of several approaches to understanding the role of individual differences in second language acquisition.