This case study documents the quality assurance strategies implemented in an online language teacher education (OLTE) program in the US. The study was conducted in a language teacher education program that has offered OLTE since 2001 and has adopted the TESOL Council for the Accreditation of Educator Preparation standards to guide the curriculum. Reviewing 16 OLTE course syllabi as well as interviewing 12 OLTE instructors, the author focuses on assessment strategies in OLTE courses to understand the ways that the program quality was assured. The study demonstrated that unit-wide key assessments were critical elements of external OLTE quality assurance. It also shows that OLTE instructors implemented more extensive formal formative assessments and provided more feedback than in traditional formats. The feedback and assessments assured the high quality of OLTE courses and held teacher candidates accountable.