There are two levels of testing that are done for ADHD, depending on the client’s needs. For adults who just need the diagnostic information for themselves of for their medical doctor, the diagnostic process includes a full background history, a limited battery of cognitive tests, and rating scales that ask about the symptoms and impact in daily life, from multiple sources whenever possible. ADHD is very much of an exclusionary diagnosis. There are any number of cognitive and emotional factors that can result in difficulties with attention; making a diagnosis of ADHD requires carefully ruling out these alternative diagnoses.
For students seeking ADHD diagnosis, there is often benefit to doing a full psychoeducational evaluation (which is described further above under the Dyslexia Testing). Students with ADHD are often able to receive accommodations in school and on high stakes tasks, but schools and testing services typically require a full psychoeducational evaluation in order to allow a student to qualify for these kinds of accommodations.