There is an increasing number of dictionary types and lexical search-tools designed to respond to an ever-growing array of user needs. The quest for innovation, however, is not over and this is what this book shall shed light on. In the autumn of 2013, a conference entitled Planning non-existent dictionaries was held at the University of Lisbon. Scholars and lexicographers were invited to present and submit for discussion their research and practices, focusing on aspects that are traditionally perceived as shortcomings by dictionary makers and dictionary users. The topics for debate were intended to be provocative: the identification of dictionary types that have never been developed for certain languages or for a given lexical domain, as well as typological and linguistic problems that may compromise the development of lexicographic projects. We hoped that the discussion would lead to the presentation of problem-solving strategies, especially those related to corpora documentation, information technology and data presentation. We received an incredible response and have had the opportunity to acknowledge several projects that are different in size, novelty and degree of accomplishment.