There is an old canard to the effect that Bolshevism was a Jewish phenomenon (the Nazis, for example, referred to it as Judeo-Bolshevism), and there are still many people today who stress the apparently disproportionate number of Jews who could be found within the Bolshevik movement - especially amongst those who held positions of power. Anecdotally, it has been my experience that Google searches lead either to material of an offensively antisemitic character ("white nationalist", and sometimes explicitly neo-Nazi websites), or to sites that refute this allegation without providing numbers or sources.
This is frustrating, since the claim gets repeated so often that I would like it verified and don't have the resources to do so reliably. I understand that by "bolshevik" we're really just referring to the majority party within the USSR (if that is correct?), and that Jewish communists didn't, by virtue of their communism, have much of a Jewish identity. I also understand that the statistics will be different if we are limiting ourselves to people who were raised as Jews, or if we broaden our scope to include people who, as per the Nazi definition, even had a single Jewish grandparent.
As such, I understand if this question might be a little too broad, and in lieu of a comprehensive answer would also appreciate references to any articles or books that address this issue in more depth. Effectively, what truth is there behind the claim that the Bolshevik movement was "disproportionately" made up of Jews, and how disproportionate was it? If Jews made up less than 1% of the population but 1.5% of the party, that would be disproportionate but hardly news-worthy.