This book is a guide to some aspects of lexical knowledge, with focus on an academic context. Carrying out academic studies in a second or foreign language requires high target language proficiency, knowledge of the given field, good literacy and study skills. A key aspect of all these is lexical knowledge and use. After a descriptive overview of vocabulary-related issues, the second part of the book presents a set of vocabulary testing case studies carried out among undergraduate students of English. As a final point, the book examines some applications of the accumulated knowledge: testing vocabulary as a diagnostic tool, predicting academic achievement on the basis of vocabulary tested at the entry point to the university, monitoring vocabulary gains, vocabulary learning strategies, and, finally, assessing the vocabulary use in students’ texts. The literature review and the methodologies used in the case studies are selective in nature and serve as a guideline for future research. The findings and the discussions are, however, relevant not only to a Central European higher education context, but to any other one in which students are expected to do work mainly in an L2.