If you don't read Science & Society, you really should.  Most of their stuff is available through JSTOR or accessible at a public library.  Their subscription is under $50 for a year from Guilford Press.  This quarter's publication in particular has a great piece by Gerald Meyer on Italian Anarchism as a movement in the United States and how it eventually diffused as a movement as the Communist Party of the United States came around in the 1920s.  For specific reference, it is Volume 79, No. 2.

It's particularly interesting in the way that Meyer navigates anarchism as a movement in the same way historians of American Communism have failed to do so, for the most part.  Then the "movement" so-to-speak, got significantly challenged by the CPUSA and its International Labor Defense (ILD), which not only "integrated the [organizing] campaign to save 'the good shoe maker and the poor fish peddler,'" but also "transformed Sacco and Vanzetti's defense"--which at the time was heavily pushed by anarchists--"into an international movement."[1]

It's really great to see scholars and writers continue to see the "movement" that is behind the organizations and Parties that came forth to represent it.  In this way, Meyer shows how there is an unignorable connection between anarchist and communist movements, particularly in their ideals among people.

But S&S is better than just that simple article.  It's a great place to see more information on American Communism as a subject as well as Marxism in general.  Not to mention, the journal has been around since 1936 as one of the leading scholarly publications for Marxist studies in the English speaking world (though it has been published in other languages.)