There is no single way of diagnosing Dyslexia. There are various kinds of tests which are used to diagnose it. Initially, tests are done to identify the presence of common symptoms, and more detailed tests are conducted to measure the symptoms. However, conducting the tests is very important if some primary symptoms are observed, as it is better to be diagnosed earlier in one's life. It is better to test and diagnose dyslexia at the age of six rather than at ten or twenty years of age. Dyslexia tests are conducted by an educational psychologist. Before consulting an educational psychologist for evaluation a medical doctor should be consulted so that physical illness is ruled out.

There are two types of tests for diagnosing dyslexia, screening tests, and comprehensive tests. A screening test is used on a large group of students to identify potential dyslexic children. A comprehensive test measures the symptoms and examines the roots of the cause of Dyslexia. Various statistical techniques are used to measure the symptoms, and it is very important for one to be aware of those measuring techniques so that they can understand the severity of the symptoms. Comprehensive tests are conducted for reading, spelling, and intelligence. Visual tests, reverse tests and sequencing tests are also part of comprehensive testing. Comprehensive testing can either be done by an educational psychologist in person, or by long distance. The test done by educational psychologists can be expensive, but it is the most effective way as the person is face to face with a psychologist. In Long distance tests the expert never gets to meet the Dyslexic person. Most of the long distance tests contain a situational questionnaire and objective questions which are to be answered and sent back. Then, the answers are evaluated, symptoms are measured, and a detailed report is sent back.

In the United States of America, as per Federal Law, a public school district is required to conduct tests for Dyslexia.