This paper is an effort to define the target of the language learner: asking, what are the data that the child pays attention to in the process of becoming a native speaker? In so doing, this paper will necessarily be engaged in the more general effort to define language itself. The general argument to be advanced here is that the human language learning capacity is outward bound, that is, aimed at the acquisition of the general pattern used in the speech community. The end result is a high degree of uniformity in both the categorical and variable aspects of language production, where individual variation is reduced below the level of linguistic significance.