I checked it out in my state and here, diagnosing is not linked to being able to prescribe. Because a therapist must be able to make a diagnosis in order to be able to give the client the right kind of treatment. So for example, a psychologist or a LCSW therapist can indeed diagnose. Also, they have to be able to put down a diagnosis to get reimbursed by insurance in my state. I don't know about ADHD, though. It probably depends on whether the therapist or psychologist is trained for that. I think there are psychologists who do have expertise in ADHD. My therapist just didn't feel like ADHD was up his alley, I think, and so he wanted to refer me out to someone with more expertise in ADHD. But he definitely diagnoses things like depression, dysthymia, bipolar disorder, GAD, panic disorder, OCD, PTSD, adjustment disorder, personality disorders, etc. If he believes the person may benefit from medication in addition to psychotherapy he refers them out to a prescriber.