From the inception of generative linguistics, both theoretical linguists and researchers in language acquisition have been concerned with the development of language knowledge in children. The second section of this chapter describes how parameters were initially stated, and where they were thought to reside in the language faculty. The third section reviews the concerns, both theoretical and empirical, raised for the early model of parameters and parameter setting, and introduces recent conceptions of parameters. The fourth section of this chapter discusses the setting of the parameter, and the fifth section of this chapter describes five recent models of parameters, which are compared with the 'classic' model of Chomsky. The chapter provides two alternatives to parameter-setting models of language acquisition, and provides two new models of parameter setting based on the findings from research on child language.