An increasing number of studies has demonstrated that learning to read and write influences the way spoken language is processed. While previous research on this field of study almost exclusively investigated orthographic effects on L1 spoken word processing, the present thesis is aimed at extending previous findings to L2 spoken word processing. In the first part of the thesis, a working model of bilingual word recognition is developed, which is able to explain orthographic and phonological interactions during L2 word processing. The architecture of the working model is based on previous outcomes of research on auditory and visual word recognition as well as current findings on orthographic influences during spoken auditory word recognition. In the second part of the thesis, the working model is tested in three psycholinguistic experiments on auditory word recognition (rhyme judgement, phoneme deletion and lexical decision). Special emphasis of the investigation lies on a cross-linguistic comparison between native and non-native speakers of English as well as between two groups of non-native speakers of English with different orthographic backgrounds, i.e. a shallow orthography (German) and a deep orthography (Danish). The results of the experiments show that orthographic information is activated during L2 auditory word processing. However, differences exist between L2 participants from a shallow and a deep L1 orthographic system. These results are discussed with reference to the working model of bilingual word recognition.