Constraints on representationIn this paper, I provide an overview of differing perspectives on the role of Universal Grammar (UG) in second language acquisition (SLA). I will suggest that we must not lose sight of the fact that UG is a theory which provides constraints on linguistic representation. At issue, then, is whether interlanguage (IL) representation is constrained by UG.UG is part of an innate biologically endowed language faculty. It places limitations on grammars, constraining their form (the inventory of possible grammatical categories, in the broadest sense, i.e., syntactic, semantic, phonological), as well as how they operate (the computational system, principles that the grammar is subject to). UG includes invariant principles, as well as parameters. While theories like Government-Binding (GB), Minimalism, or Optimality Theory differ as to how precisely they handle concepts like principles and parameters, there is a consensus that certain properties of language are too abstract, subtle and complex to be learned without postulating innate and specifically linguistic constraints.