The aim of my thesis is to investigate the underlying reasons behind students’ relative underachievement in grammar acquisition. In particular, I attempt to find possible answers to the question of why university level English language students seem to have difficulty in the adequate use of a certain grammatical structure or word class – which are, in this case, the definite and indefinite articles – after they have been exposed to several years of explicit language instruction and do supposedly possess a large amount of relevant theoretical knowledge. The thesis is comprised of two major parts. Initially the Review of the Literature provides a selection of relevant previous academic exploration in this field. This literary review comprises of sources the thesis intends to draw on to provide a foundation upon which to implement the study. Subsequent to this, the second part (The Study) I describe the method, implementation and analysis of the small scale research I carried out within the scope of this thesis.