The incel (involuntary celibate) community is an extremist online community that practices intense misogyny, racism, and that glorifies – and sometimes practices – violence. Work to understand the dynamics within incel communities has been hindered by the fact that these communities are spread over many platforms and many of the more popular forums of the past have been banned and their content deleted. In this paper, we present two main contributions. First, we introduce a carefully reconstructed, nearly complete archive of incel forums dating back to 2016, including millions of posts that can no longer be accessed. Then we illustrate a technique for identifying community-specific language and using that as a marker of extremism to track radicalization over time.