Cap. 1 Introduction. -- Cap. 2 The dynamics of Disease Transmission. -- Cap. 3 Measuring the Ocurrence of Disease: I. Morbidity. -- Cap. 4 Measuring the Ocurrence of Disease: II. Mortality. -- Cap. 5 Assessing the Validity and Reliability of diagnostic and Screening Tests. -- Cap. 6 Tha natural History of Disease: Ways of Expressing Prognosis. -- Cap. 7 Assessing the Efficacy of Preventive and Therapeutic Measures: Randomized Trials. -- Cap. 8 Randomized Trials: Some Further Issues. -- Cap. 9 Cohort Studies. -- Cap. 10 Case - Control Studies amd Other Study Designs. -- Cap. 11 Estimating Risk: Is There an Association?. -- Cap. 12 More on Risk: Estimating the Potential for Prevention. -- Cap. 13 A Pause for Review: Comparing Cohort and Case - Control studies. -- Cap. 14 From Association to Causation: Deriving Inferences from Epidemiologic Studies. -- Cap. 15 More on Sausal Inferences: Bias, Confounding, and Interaction. -- Cap. 16 Identifying the Roles of Genetic and Eviromental Factors in Disease Causation. -- Cap. 17 Using Epidemiology to Evaluate Health Services. -- Cap. 18 The Epidemiologic Approach to Evaluating Screening Programs. -- Cap. 19 Epidemiology and Public policy. -- Cap. 20 Ethical and Professional Issues in epidemiology. --