Yeah for students wants alternate Greek organization. There are a few that don’t participate in formal rush.
Alpha Delta Chi : is a Christian sorority. Last I saw they have about 70 members. Great group of girls that I think is an alternative for those who want a sisterhood that’s faith based.
Sigma Delta Tau : traditionally Jewish sorority. They are open to girls of any faith. They have a house on campus. I believe they’re smaller than 50 members.
Alpha Omega Epsilon: engineering sorority. It’s currently a colony not an official chapter. But they seem to have a lot of fun also.
Theta Tau: engineering co-ed fraternity. They have a house on campus and are very active. I have many friends in theta tau. They provide both professional and social events.
There are more specific groups also like music sorority and fraternity, honor societies. But these are the most common ones I know that don’t participate in formal rush. I know people in all of them and everyone seems to love them.