The present collection stems from the 1st NetWordS Workshop "Understanding the architecture of the mental lexicon: Integration of existing approaches", held in the Pisa Research Area of the Italian National Research Council, in November 2011. "NetWordS: the European network on Word Structure in the languages of Europe" is the Research Networking Programme of the European Science Foundation launched in May 2011 with the ambitious goal of paving the way to the European interdisciplinary research agenda on the Mental Lexicon, with particular emphasis on the following three main challenges: - lexicon and rules in the grammar, - word knowledge and word use, - words and meanings.