ABSTRACT
Depth of vocabulary knowledge is typically defined as how well a word is known. Thus, measuring depth of vocabulary knowledge should tell us how well test takers know words. The importance of knowing vocabulary deeply is based mainly on two ideas: (1) L2 learners have to know different aspects of word knowledge in order to fulfill communicative tasks (i.e., reading, listening, writing, and speaking), and (2) advanced learners who can use vocabulary proficiently can demonstrate different aspects of knowledge of words. For example, knowledge of spelling is required for writing; knowledge of pronunciation is necessary for speaking; and knowledge of collocation is needed for both of these skills. Moreover, to use words appropriately, learners also have to know the contexts where specific words should and should not be used. Tests of vocabulary depth are thus of great value because they may signal the extent to which students have the knowledge to use vocabulary proficiently.
There are now many studies that have investigated depth of vocabulary knowledge. Studies vary greatly in their conceptualization and measurement of vocabulary depth. This chapter provides an overview of how depth has been defined and investigated. Moreover, the chapter discusses important topics related to measuring depth of vocabulary knowledge and looks at questions such as: To what extent can depth of vocabulary knowledge be measured? Which aspects of vocabulary knowledge should be measured? Which words should be measured?
