These “500 questions, answers, and explanation” books are designed to simulate the United States Medical Licensing Examination (USMLE) Step 1. Each is authored by an expert in the field and has been reviewed by students who have recently passed the exam. As Step 1 is becoming increasingly more clinical in nature, when applicable, clinical vignette-style questions requiring a two-step reasoning process are also included. All of the Pretest titles include a “high-yield” fact section to reinforce key concepts.