Tests are a necessary aspect of teaching English to speakers of other languages (TESOL). For an educator it is crucial to monitor the progress of the learners and be aware of difficulties they may experience. Testing is a suitable way for the teacher to observe the learner’s success and failure and make conclusions considering the methods and approaches implemented for each specific learner or class (Hancock, 2006). There are a number of various tests designed to determine the learners’ progress in each aspect of English such as proficiency, vocabulary, skills and knowledge, theoretical and practical application of language. This paper focuses on ten different types of tests and their use for TESOL. Proficiency tests are normally composed of several levels. This is done in order to determine the learner’s proficiency in various spheres such as grammar, vocabulary, and text comprehension. Tests of thins kind are based on multiple choice scheme so the learner needs to select one of the offered answers. The questions of such test are selected in order to target different aspects of the English grammar and also the learners’ ability to read and understand written text. Proficiency tests are good for TESOL educators because they serve as a perfect tool for monitoring general progress, the efficiency of various teaching methods and the level of knowledge and skills of learners at various stages. Diagnostic tests are rather specific; they are also recognised as progress tests. They are called this way because they are designed to diagnose certain aspects of language and the level of the learners’ progress (Gonzalez, 1996). The tests of this type are often conducted in the end of a unit and are directed at the determination of the knowledge the students acquired and the skills they obtained. These tests are normally based on short-term objectives. Since teaching English to the speakers of other languages is always broken down into units, diagnostic tests serve as useful means to estimate the quality of learning and to determine if the students can move on to the next stage based on their progress level. Placement tests represent a particular kind of diagnostic tests (Brown, 2003). They are designed to cover the materials within a certain curriculum. They are conducted with the purpose to determine where the students are to be placed in relation to the information studied by specific learners. In TESOL this kind of tests is useful because they help to save time and effort to both educators and students and place the learners exactly where they need to pick up from instead of making them go through certain materials for the second time. Achievement tests can be viewed as a kind of progress or diagnostic tests because the main objective of these tests is to evaluate the knowledge of a learner within a particular curriculum, program or unit. The length of the period of time covering certain material or program evaluated by the test is indefinite, and this is why the tests are called “achievement” instead of “progress”. Achievement tests are oriented at the evaluation of specific kinds of knowledge, which is useful in TESOL because this allows estimating the quality of the program,