This is essential to prepare for the PRAXIS I exam. Since it is published by ETS who creates the exam itself, you get a realistic idea of the level of study required and the practice tests are authentic. A good method is to start out by using the ARCO series "Everything you need..PRAXIS I PPST" guide for studying and practicing on their tests, and then take the practice tests in this ETS guide. It gave me a lot of confidence that I was studyging the right material and I did very well on the tests.