There is a demand for a practical book on auditing which up to this time has not been met. If my twenty-four years of continuous experience in professional accountancy work is a sufficient practical training, I trust I have established a prima facie excuse for the presentation of this book, which contains more of practice than of theory. Auditing, in its broadest sense, is the most important branch of accountancy. During the early years of my clerkship in the office of Mr. John Heins, of Philadelphia (then President of the American Association of Public Accountants), and later, while acting as an instructor in the School of Accounts and Finance of the University of Pennsylvania, I strongly felt the need of a dependable textbook on the subject. My attention was all the more directed to the paucity of books on auditing and on other accounting and cognate subjects by contrast with the full and comprehensive literature of the legal profession which I had found of such great assistance in my studies preparatory to admission to the bar.