The majority of words in most languages consist of derived poly-morphemic words but a cross-linguistic review of the literature (Amenta and Crepaldi in Front Psychol 3:232-243, 2012) shows a contradictory picture with respect to how such words are represented and processed. The current study examined the effects of linearity and structural complexity on the processing of Italian derived words. Participants performed a lexical decision task on three types of prefixed and suffixed words and nonwords differing in the complexity of their internal structure. The processing of these words was indeed found to vary according to the nature of the affixes, the order in which they appear, and the type of information the affix encodes. The results thus indicate that derived words are not a uniform class and the best account of these findings appears to be a constraint-based or probabilistic multi-route processing model (e.g., Kuperman et al. in "Lang Cogn Process" 23:1089-1132, 2008; "J Exp Psychol Hum Percept Perform" 35:876--895, 2009; "J Mem Lang" 62:83-97, 2010).