The convention called in accordance with the Manifesto of the January conference met two hundred strong in Chicago on Tuesday, June 27, 1905. This gathering was first referred to as the "Industrial Congress" or the "Industrial Union Convention," but since before adjournment it had organized itself as the Industrial Workers of the World, it is referred to as the First Annual Convention of the I. W. W. It was a gathering remarkable and epoch-making in more ways than one, and therefore the story of its activities is essential, not only to an understanding of the subsequent career of the organization, but as a fundamental chapter in the whole history of industrial unionism. The discussions and resolutions of the assembly and the final type of organization which grew out of them can be understood only in the light thrown on them by a study of the composition of this revolutionary group of men. Its occupational, structural, and doctrinal character should each be taken into account.

Perhaps the most striking characteristic of this group of two hundred radicals was the bewildering range of occupations represented. The variety of different trades represented and the varying "quality" levels exhibited in the organization here gathered to sink all differences and become as one, were astonishingly great. The following list of the different organizations represented at the convention reveals at least forty distinct trades or occupations:

The foreign organizations were each represented by at least one delegate with full powers and instructions. The following named bodies sent uninstructed delegates:

Aside from the occupations represented above, the following were each represented by one or more individuals: machinists, tanners, electrical workers, bookbinders, editors, teachers, authors, printers, and shoe workers. An attorney-at-law from New York City presented himself at the convention. The committee on credentials recommended that he be seated as a fraternal delegate, on account of the mitigating circumstances that he wrote for several newspapers and was a "friend and sympathizer" of labor. After considerable debate the report of the committee was adopted "with the exception of that portion which refers to the attorney."[98]

This array of occupational or trade types was scarcely more extensive than that of the structural types here grouped together. Of these there were the following types. (1) the simple industrial union, wherein all workers engaged, in whatsoever capacity, in any particular industry are members of the same union. This type was represented by the Western Federation of Miners[99]—really the strongest taproot of the I. W. W. (2) The multi-industrial type, a federation of industrial unions, such as the American Labor Union, which included railway employees, engineers, and musicians. (3) The so-called "international" union, rarely more than national in scope, and merely a national association of local unions of a given trade. This type was represented by the United Metal Workers International Union of America. (4) The non-federative industrial union, like the United Mine Workers of America with industrial rather than trade units, an industrial organization which excludes federation with similar organizations in other industries, or with employers. (5) The ordinary non-federative trade unions, here seen in two types: (a) the trade amalgamation, a federation of unions wherein the constituent bodies are so united as to preserve their individuality, although trade autonomy is thereby destroyed. This type is illustrated here by the Amalgamated Society of Engineers; (b) national unions of any particular trade like the iron molders, wherein the constituent unions are more subordinated to the national body than in the amalgamation. (6) The state federation—as typified by the Utah State Federation of Labor. And finally (7) the rather unconventional type of "union," represented by the Industrial Workers' clubs and the United Labor League.

It should be understood that but a small part of the "international" or national bodies was represented as a whole. The greater number were represented by one or two locals. A number of them were affiliated with the American Federation of Labor at the time, but had become dissatisfied with the policies of that body.[100] However, some of the unions most prominent in the activities of the convention were represented as central or national bodies with all their constituent local unions. Such were the American Labor Union and the United Metal Workers.

Those of the unions present which were affiliated with the American Federation of Labor, though forming a fairly large group numerically, represented no material defection from the ranks of the Federation and, generally speaking, played but a passive rôle in the work of the convention. Of the forty-three organizations seated by the credentials committee sixteen were affiliated with the Federation, but at least eleven of these were represented by but one local union. Of all these organizations which had merely local rather than national representation, the United Mine Workers of America was most widely represented, delegates from nine of its local unions being present.[101] A little study of the list of the organizations seated and the localities from which their delegates came, makes it quite evident that on the whole the strong delegations from powerful local bodies, located at strategic points, were those having no connection with the American Federation of Labor, and, conversely, that the fourteen American Federation of Labor unions just referred to were represented as a rule by small and solitary locals of doubtful strength.[102] The insignificant position of the American Federation of Labor bodies in the convention will become still more manifest by an inspection of the lists given above.[103] It will be seen that only five of the sixteen local unions of the American Federation of Labor which were present had empowered their delegates to install their respective local unions in the new organization: two locals of the United Mine Workers and one local each in the Bakers and Confectioners, the Brewery Workers and the Journeymen Tailors unions. All the locals of the United Metal Workers were so empowered. The American Federation of Labor was represented in no direct way among the five great powers of this industrialist convention.[104]