Primary stress assignment is a recurrent open issue in the literature on Italian phonology. One of the most controversial points concerns the lexical vs. regular nature of stress in this language. Both positions have advantages and drawbacks. In particular, as far as the 'lexical' hypothesis is concerned, if stress assignment is not governed by rules, it should be explained why speakers, in general, make similar choices when asked to assign stress to novel/unknown words. In this paper we observe that, while some purely phonological rules of stress assignment may be active in the language, they are not always sufficient to predict stress position. We hence propose a more global approach, in which other factors also play a role. We present the results of two experiments, an informal test of reading of pseudo-words, and an auditory word recognition experiment showing the role of non-phonological factors in stress assignment, such as identification of a form as belonging to a specific lexeme, segmental similarity with other words in the language, and neighbourhood density of a word.