The book 'National Science Olympiad' Has been divided into five sections namely Science, Logical Reasoning, Achievers section, Subjective section, Model Papers. In every Chapter, the theory has been explained through solved examples, illustrations and diagrams wherever required. Multiple choice questions (MCQs) with detailed solutions are provided in the end of each Chapter to enhance the problem solving skills of candidates. The questions in the Achievers section are set to evaluate scientific skills of brilliant students whereas the subjective section includes questions of descriptive nature. Two Model Papers have been included to do practice on the expected questions. A CD containing Study Chart for systematic preparation, Tips & tricks to crack Science Olympiad, Pattern of exam, and links of Previous years papers is accompanied with this book. The book is also useful for various competitive exams such as NTSE, NSTSE, and SLSTSE as well.