My son was tested at 4 also, for entrance to K. We used the WPPSI b/c it was required by the school. I would say that the most important piece of the process is choosing the right person to give the test. We used a woman recommended by our local gifted private school. They told me that she was the only person they regularly recommended because of her many years of experience, reasonable cost to parents, and knowledge of gifted kids. I was actually in the room when the test was given (she gave DS the option, so of course he asked that I stay!) so I got a chance to watch her in action and she was great with him. She had the room set up so that even though I stayed my back was to him while they were working, so I wasn't standing there looking over his shoulder, but I was present. It blew my mind how skilled she was at keeping him on task and encouraging him to do his best. My son is very intense and usually does things only to suit himself, never to please others. He is also an extreme perfectionist. The psychologist picked up on this and later told me that she used "her whole bag of tricks." For example, she told him that when she asked a question of him, then he could ask one back of her. She told him that if he would do his best to answer as if she were an alien from another planet and knew nothing about things here on earth then she would do her best to answer his questions. So, some of her questions seemed totally ridiculous (for example, things like "What is a pencil?" Of course, this is not the exact question). Anyway, since she asked him to answer as if she were an alien he totally caught on. Then he asked his questions--things like "What makes us alive?" and "What makes plants grow?" Of course, she cracked up answering these and it also gave her lots of info about my son. When she came to a question that she thought might be challenging to him, she would encourage him to prevent him from giving up and not trying because of his perfectionism. He did very well on the test, and I am sure that he could have done terribly with an inflexible, inexperienced tester. So, that would be my biggest recommendation. Ask the tester what they do for small children and how they find the most reliable scores for children who are young, gifted, perfectionists, or cantankerous! (My son was all four!) Good luck to you!