Anarcho-syndicalism.

One of the first books (different edition though) I have read about anarchism (and syndicalism) as kid and right away I felt like this really is my thing! After that I've read it couple of times atleast and even have few different editions of it.

Rocker does a lot of great service in presenting historical currents and events in his detailing of anarchist movements, revolutions and ways in which the communities in question organised themselves, however I found a little less in the way of theoretical exploration of concepts than expected.