the psychologist who will be doing my son's eval next month uses either the wppsi or das.i have noticed some of the private schools i have read about ask for the wppsi....but when i read online about the das i like it because it looks like it includes achievement tests in spelling, math, and reading as a subtest. these are the areas where my son really blows me out of the water. so now i am confused as to which test is best? any ideas?