This entry focuses on quality assurance (QA) in online language testing. The entry begins with the definition of QA in testing from a broad view of assessment. Then, it explains the scope of ensuring quality in online language testing. Additionally, the entry presents the main components required for establishing quality in online language testing, both qualitatively and quantitatively, in light of reliability, validity, and practicality. Linking the concept of QA with online language testing, the entry provides the pedagogical basis to be considered with support from current theories and proposals for the practices in educational contexts to ensure quality.