Some ways are available to getting diagnosed with ADHD, and think few are more powerful and accurate than others. The most powerful and successful way to get tested, in my opinion, is by a psychologist or psychiatrist trained in ADD and learning disabilities.
Because ADD often is accompanied by other learning disabilities, testing for these is also helpful. It would also be helpful to test for learning disabilities to make sure that ADD symptoms are not really a learning disability in disguise.
The formal testing done by a licensed mental health professional are long and costly, but in the end they are worth the time, effort and money invested in them. If the individual tested does come to be diagnosed with ADD, it is a sound diagnosis that has been thoroughly evaluated and tested. Individuals can have confidence in what they have been told and move on to the next step in their recovery.
If they are told they do not have ADD, they again know they can trust who is telling them this and feel relief that they do not have to struggle with the disorder. This may mean they have some other learning disability or psychological issue, but they will be given the right direction to follow from an educated professional.
Another route that people are diagnosed is again through a psychologist or psychiatrist, but here a long history is taken of the individual. Report cards and other formal documents are looked through and family members are interviewed. The licensed professional attempts to get a clear picture of the issues the individual faces, and they try to see how long their problems have been going on. Depending on who they are testing, the process can be long or short, simple or complicated. This method also provides educated answers, and the individual being interviewed/evaluated should have confidence in their diagnosis.
There are a couple other ways that individuals are diagnosed with ADD that are not nearly as effective and can lead to misdiagnosis. Some school professionals such as guidance counselors have diagnosed kids with ADD in the past, and I honestly do not believe they have the education or tools that are necessary to do this. Giving someone an ADD diagnosis changes their life, and should be given with care. Also, some people may think they have ADD and get a referral to a psychiatrist. Some psychiatrists may ask you a few simple questions and then hand you a prescription for stimulants.This method of diagnosis is little uncomfortable. A short questionnaire will not tell you whether someone has ADD, and this way of diagnosing I have no self-esteem in.