The purpose of this book is to estimate the effect of all U.S. taxes on the distribution of income by size of income and by other taxpayer characteristics. The book is concerned solely with the distribution of tax burdens, without any reference to the distribution of the governmental benefits that are supported by taxes. Based on an analysis of 1966 income and tax data for a representative sample of 72,000 American families, it attempts to show how the actual distribution of disposable income differed from what the distribution would have been if all tax revenues had come from a proportional income tax with the same yield. The authors conclude that the U.S. tax system is essentially proportional for the vast majority of families and therefore has little effect on the overall distribution of income. Detailed descriptions of the sources, the methods, and the basic statistical data developed for the study are given in the appendixes. (Author/JG)