This volume brings together a collection of chapters focused on the learning, testing, and researching of L2 vocabulary by leading international researchers including Paul Nation, Batia Laufer, Frank Boers, Elke Peters, Ana Pellicer-Sanchez, Anna Siyanova-Chanturia, and Stuart Webb. Questions that are examined include: Is it useful to read a book to learn vocabulary? Which types of input encountered outside of the classroom contribute most to vocabulary knowledge? What are the most useful words to learn to understand the academic spoken language in mathematics, biology, and engineering lectures? Does writing words contribute to vocabulary learning? What should a test measuring the skill of guessing from context consist of? Should loan words be included in vocabulary tests? How should we evaluate vocabulary learning that occurs through watching captioned video? How has eye-tracking been used in vocabulary research? Together, the chapters in this volume highlight innovation in vocabulary studies and many directions for researching, testing, and learning words. Originally published as special issue of ITL - International Journal of Applied Linguistics 169:1 (2018)