Validation is an activity that establishes the extent to which a language assessment is meaningful and useful. This activity involves the collection of different types of evidence in order to make a holistic evaluation of an assessment's fitness for a purpose. Several frameworks have been introduced to guide the collection and evaluation of this evidence for language assessments, and the argument‐based approach has become increasingly prominent. This entry outlines the consensus view of validation, highlights prominent validation frameworks and their extensions, and provides a brief overview of prevailing concerns for validation.