Abstract: Drawing from a corpus of over 50 million Russian-language tweets collected between March 2010 and March 2011, we created a network map of 10,285 users comprising the ‘discussion core,’ and clustered them based on a combination of network features. The resulting segmentation revealed key online constituencies active in Russian Twitter. The major topical groupings in Russian Twitter include: Political, Instrumental, CIS Regional, Technology, and Music. There are also several clusters centered on Russian regions, which is significant given the limited reach of the Internet in the regions outside of Moscow and St. Petersburg. Russian Twitter features a great deal of activity generated by marketing campaigns and search engine optimization (SEO) initiatives, including both automated and coordinated human actors. After our initial mapping resulted in a network dominated by these ‘instrumental’ actors, we constructed a filter to limit their presence in the network and discover relationships among a wider variety of ‘organic’ actors. Similar to the Russian blogosphere, the Twitter network includes a democratic opposition cluster associated with Gary Kasparov and the opposition Solidarity movement.1 In other respects the political clusters identified in Weblog and Twitter networks display interesting variation. Nationalists, who are very active in Russian blogs, do not appear to be organized in Russian Twitter (at least as of March 2011). Conversely, pro-Putin youth groups like the Young Guards and Nashi, and elected officials allied with them, have a distinct Twitter footprint. While other clusters within Twitter often mirrored those in Weblogs, such as one cluster focused on major bloggers and online personalities, there were some Twitter clusters that had no clear Weblog analog. Most notably, there are two clusters of Twitter users affiliated with local government administrations in Tver and Ivanovo, representing active outreach to citizens by local government actors. While the filtered version of the map successfully reduced the presence of SEO actors, it curiously eliminated a pro-government cluster as well. In the filtered map, whereas the number of political actors was greatly increased overall, a cluster in the original map that focused on President Medvedev’s economic modernization policy disappeared, along with related hashtags. One possibility is that, as we observed in the Russian blogosphere, some political initiatives have adopted the tactics and/or services of online marketers.