This article offers an insight into useful methods of evaluating language proficiency in students. It focusses on a couple of essential principles for valid and fair testing. Starting from three basic questions a teacher must consider before drawing up a test (why, what and how), the article discusses the different reasons for testing. Finally three criteria for quality (validity, consistence and achievability) are taken into account, as well as possible distortions created by different tests in different contexts. The article concludes with a statement about the importance of variation and the critical approach of tests as good testing is important for both teachers and students.