This text is designed for an introductory probability course taken by sophomores,juniors, and seniors in mathematics,the physical and social sciences,engineering,and computer science.It presents a thorough treatment of probability ideas and techniques necessary for a firm understanding of the subject. The text can be used in a variety of course lengths, levels,and areas of emphasis.For use in a standard one-term course,in which both discrete and continuous probability is covered, students should have taken as a prerequisite two terms of calculus,including an introduction to multiple integrals.In order to cover Chapter 11,which contains material onMarkov chains,some knowledge of matrix theory is necessary.Very little computing background is assumed or necessary in order to obtain full benefits from the use of the computing material and examples in the text.All of the programs that are used in the text have been written in each of the languages TrueBASIC, Maple, and Mathematica.