In this book the author who was the principal investigator of the national HIV/AIDS behavioral surveillance surveys has analyzed and reported a large secondary data set with a sample of 14, 524 respondents covering over ten adult sub populations that are considered important to monitor levels of HIV risk in Ethiopia. Analysis of behavioral responses on such a scale is very rare even at global level. Therefore the book demonstrates the relevance of examining large data sets to come up with better power of concluding points that will assist national HIV/AIDS prevention and control programs. The book examines the relationship between HIV/AIDS knowledge of different range including knowledge of preventive methods and rejection of prevailing misconceptions versus practice of self protective behavior such as consistent condom use, condom use at last sex, faithfulness and others among the different populations. Behavioral indicators of female sex workers are compared at two points in time to illustrate the contributions of the high risk group in driving the HIV/AIDS epidemic in Ethiopia. Some of the findings in the book are also found published in peer reviewed journals.