DIALANG is an on-line language assessment system, which contains tests in 14 European languages and is based on the Common European Framework of Reference (CEFR). It is the first major testing system that is oriented towards diagnosing language skills and providing feedback to users rather than certifying their proficiency. This article describes the contents of Version 1 of DIALANG and the way in which the system works. This is followed by an account of the development of DIALANG tests and of the pilot testing and standard setting procedures. The results of the first analyses of items and self-assessment statements, and of the standard setting procedures, are reported. The article focuses on the results for English, but findings for some other languages are also touched upon.