To make the quality of language instruction transparent and to guarantee this quality, the use of external quality assurance procedures is recommended for DaF (German as a Foreign Language) teaching and DaF language institutes. However, little is known so far about the effectiveness and limitations of these procedures. The author focuses on quality assurance in the field of German as a foreign language. She starts with a description of DaF instruction in the context of political and economic conditions and examines the external procedures EAQUALS, ISO 9000 ff., and IQ Deutsch for their suitability for the DaF sector. The central focus of the work is on the experiences of certified language institutes with these procedures and the impact these procedures have on teaching and organization. The possibilities and limitations of external procedures are also considered.