LAL was originally derived from assessment literacy in general education. Coined by Stiggins (1991), assessment literacy as a term refers to the knowledge and skills an assessment-literate person (teachers, school administrators, test users, etc.) needs to construct, administer, or complete designated assessment tasks. Since then, its scope has been broadened. Drawing on assessment literacy, the term “language assessment literacy”, used by Inbar-Lourie (2008) for the first time, shares the general qualities with assessment literacy but keeps its unique feature. In other words, LAL embeds language construct into knowledge, skills, and practices in testing and assessment (Harding, 2016; Inbar-Lourie, 2008). This chapter reviews LAL definitions, frameworks and existing studies related to language teachers’ LAL status quo and development. Teachers’ assessment identity along with their LAL development is also reviewed and discussed. Based on the review, a theoretical framework and two main research questions are proposed to inform and guide the current study.