This is an introductory textbook covering the mathematics of interest rates, life contingencies and loss models. It can be adopted as (1) the main text of a one-semester first course in the mathematics of interest rates and actuarial mathematics, using selected chapters and sections, (2) as the main text of a one-semester first course in the mathematics of interest rates and investments, using all chapters in Part I, or (3) as a supplementary text of a one-semester first course in actuarial mathematics, using all chapters in Part II.