The existence between 1908 and 1915 of two national labor organizations bearing the name, Industrial Workers of the World (or "I. W. W."), with labels of identical design--bodies closely paralleling each other in scope and structure despite their disparity in doctrine and tactics--makes it very difficult to discuss either group, or I. W. W.-ism in general, without ambiguity. The I. W. W. which has been most advertised in the United States is the Chicago, or "Direct-Actionist," or "Anarcho-Syndicalist," or "Anti-Political," or "Bummery" or "red" I. W. W. This is the I. W. W. which was actively interested in the strikes at Lawrence, Massachusetts, Wheatland, California, and many other places, and in "free speech" fights at Spokane, Fresno, and San Diego. They are the "Wobblies" of the West. In this present work they are considered, entirely without prejudice to the admittedly more "correct" and consistent position of the doctrinaires of the Detroit wing, to be _the_ I. W. W. The doctrinaires are the socialistic, pro-political, "yellow" I. W. W. It is proposed in these chapters to sketch the main lines of development of the Chicago organization from 1908 to the present time, as well as to indicate the general character of its activities from year to year. The important and bitterly fought struggle at the seventh and eighth conventions in 1912 and 1913 over the question of decentralization is described as faithfully as possible. The relations between the I. W. W. and the Socialist party are set forth, especially in connection with the adoption of the famous _sabotage_ clause by the Socialist party at its Indianapolis convention in 1912. The newer phases of the organizing and propaganda work of the I. W. W., the free-speech fights, and its increased activity among the unskilled and floating laborers are described. No attempt is made here to go into the various strikes and free-speech controversies in more than a very cursory manner. This is not because their importance is underestimated. The writer feels that the field work of the "Wobblies" is really the most significant part of their history, if for no other reason than that the I. W. W. expends perhaps more energy in proportion to its strength and resources in propaganda, organizing and advertising work afield than does almost any other labor organization in the country. The more striking episodes in the career of the I. W. W., like the Lawrence strike and the Wheatland hop riots, have, however, been extensively written up in the magazines and recorded as well in scientific journals and government reports. On the contrary, the vicissitudes of the career of the I. W. W. as an organized body of workers have never even been recited.