A U-DOP approach to modeling language acquisition Margaux Smets Abstract: In linguistics, there is a debate between empiricists and nativists: the former believe that language is acquired from experience, the latter that there is an innate component for language. The main arguments adduced by nativists are Arguments from Poverty of Stimulus. It is claimed that children acquire certain phenomena, which they cannot learn on the basis of experience alone ---and therefore, there has to be some innate component for language. In this thesis, we show that at least for certain phenomena that are often used in such arguments, it is possible to explain how children acquire them on the basis of experience alone, viz. with an Unsupervised Data-Oriented Parsing (U-DOP) approach to language. In the first part of the thesis, we develop concrete implementations of U-DOP, and contribute to the field of unsupervised parsing with two innovations. First, we develop an algorithm that performs syntactic category labeling and parsing simultaneously, and second, we devise a new methodology for unsupervised parsing, which can in principle be applied to any unsupervised parsing algorithm, and which produces the best results reported on the ATIS-corpus so far, with a promising outlook for even better results. In the second part of the thesis, we then use these concrete implementations to show how the acquisition of certain phenomena can be explained in an empirical way. We look in detail at wh-questions, and then show that the U-DOP approach is more general than the nativist account by looking at other phenomena.