The purpose of this book is to conceptualise the research on dictionary use within a more general overview of language learning. It brings together some of the findings of studies on dictionary users and uses and shows how research into dictionary use can contribute to the improvement of dictionary design and the clarification of issues in language learning. The book also provides reports on a series of empirical studies on dictionary use in decoding activities (reading comprehension and L2/L1 translation) , which will shed some light on the nature of the issues discussed throughout the book. The book falls into two parts. Part I, »Research on Dictionary Use - State of the Art« is, as its title suggests, a summary of previous studies to tease out relevant issues in each area of inquiry. Part 2, »Empirical Studies« reports on a series of studies the author has conducted in the past 15 years. The first three studies (Chapter 5, 6, and 7) investigate dictionary use in the broader context of language learning. The next four studies (Chapter 8, 9, 10 and 11) report on a series of controlled experiments on the relationship between the macro- and microstructure of the dictionary and reference skills. Finally, the last two chapters (Chapter 12 and 13) report the use of learner language data for a better lexicographical output.