This document provides information about diagnostic tests. It begins by defining diagnostic tests as tests designed to diagnose specific aspects of a language and help teachers and learners identify problems. Examples of diagnostic tests given include pronunciation tests, grammar tests, and unit pretests. A pronunciation test example involves learners reading a passage while recorded and being analyzed on stress, rhythm, intonation, vowels, and consonants. A grammar test offers information on verbs, tenses, modals, and other parts of speech. The document also provides tips for creating diagnostic tests such as assessing specific skills and accounting for all components of the skills being tested.