Free association, free association of producers or the association of free and equal producers, refers to the relations of production in communism. It means that in communism, workers will participate with other workers in free, egalitarian decision making, while their interpersonal association (speech, love, etc.) is free from taboo.
Thousands of cooperatives all of the world attest to this. As Marx noted in 1864: "there was in store a still greater victory of the political economy of labor over the political economy of property. We speak of the co-operative movement, especially the co-operative factories raised by the unassisted efforts of a few bold “hands”. The value of these great social experiments cannot be overrated. By deed instead of by argument, they have shown that production on a large scale, and in accord with the behests of modern science, may be carried on without the existence of a class of masters employing a class of hands; that to bear fruit, the means of labor need not be monopolized as a means of dominion over, and of extortion against, the laboring man himself; and that, like slave labor, like serf labor, hired labor is but a transitory and inferior form, destined to disappear before associated labor plying its toil with a willing hand, a ready mind, and a joyous heart."