Until now, learner lexicography has been based more on lexicographic principles than on empirical knowledge of user needs. This book outlines some investigations into the use of dictionaries by intermediate learners. Research was aimed at identifying problems encountered by learners during dictionary consultation, as well as factors that help or prevent the understanding of dictionary definitions. The results show that actual user needs and reference skills do not coincide with lexicographers' assumptions, and have led to a number of specific lexicographic and pedagogical recommendations.