The Less Wrong meetup in Columbus, OH is very oriented toward popularizing rationality for a broad audience (in fact, Intentional Insights sprang from this LW meetup). We've found that doing in-person presentations for secular groups is an excellent way of attracting new people to rationality, and have been doing that for a couple of years now, through a group called "Columbus Rationality" as part of the local branch of the American Humanist Association. Here's a blog post I just published about this topic.
Most importantly for anyone who is curious with experimenting doing something like this, we at Intentional Insights have put together a “Rationality” group starter package, which includes two blog posts describing “Rationality” events, three videos, a facilitator’s guide, an introduction guide, and a feedback sheet. We've been working on this starter package for about 9 months, and finally it's in a shape that we think it's ready for use. Hope this is helpful for any LWs who want to do something similar with a secular group where you live. You can also get in touch with us at info@intentionalinsights.org to get connected to current participants in “Columbus Rationality” who can give you tips on setting up such a group in your own locale.
It seems like the target audience in this case are secular groups like atheist groups. Atheists groups currently form over being against theism which gets boring with time. I think those groups should be open to rationality if the pitch is right.
Yup, all depends on the pitch - I answered a question about pitching it below.