This graduate-level textbook appeals to readers interested in the mathematical theory of disease transmission models. It is self-contained and accessible to readers who are comfortable with calculus, elementary differential equations, and linear algebra. The book provides insight into modeling cross-immunity between different disease strains (such as influenza) and the synergistic interactions between multiple diseases (e.g., HIV and tuberculosis); diseases transmitted by viral agents, bacteria, and vectors (e.g., mosquitos transmitting malaria to humans); and both epidemic and endemic disease occurrences. Audience: This text is appropriate for graduate-level courses in epidemiology for students in mathematics departments as well as for students in epidemiology programs who have a strong background in mathematics. It will also be of interest to researchers with backgrounds in the epidemiological, mathematical, and medical sciences and individuals involved in the development, implementation, and evaluation of public health policy. Contents: Lecture 1: Compartmental Epidemic Models; Lecture 2: Models for Endemic Diseases; Lecture 3: Heterogeneity in Epidemic Models; Lecture 4: Models Structured by Age; Lecture 5: Models for Diseases in Highly Mobile Populations; Lecture 6: Modeling Influenza; Lecture 7: Models for the Dynamics of Influenza; Lecture 8: Models for the Transmission Dynamics of HIV; Lecture 9: Dynamical Models of Tuberculosis and Applications; Lecture 10: Models for Sexually Transmitted Diseases.