From their meetup page:
"ChicagoVeg is the largest Chicagoland community for vegetarians, vegans, and raw foodists to socialize and meet like-minded people. We organize a range of fun activities and educational events in the city and the suburbs. Whether you are vegan or not vegan, we welcome everyone who is interested in a vegan/vegetarian/raw lifestyle for any reason - ethical, environmental, health, or spiritual. "
Meetup site: http://www.meetup.com/ChicagoVeg/
They also have several sub-groups.