In this paper we present PaCCSS--IT, a Parallel Corpus of Complex--Simple Sentences for ITalian. To build the resource we develop a new method for automatically acquiring a corpus of complex--simple paired sentences able to intercept structural transformations and particularly suitable for text simplification. The method requires a wide amount of texts that can be easily extracted from the web making it suitable also for less--resourced languages. We test it on the Italian language making available the biggest Italian corpus for automatic text simplification.