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You'll want to get in touch with Student Gov't and find out how you establish a campus organization. You may need a set number of charter members-- talk to your friends. From there, you can brainstorm a name, a mission statement, colors and symbols and an ongoing charity project that is meaningful to you and your mission. Come up with a social and service calendar. Invite members from other student organizations to pair up with you at these events. Invite them to join you. If there are fraternities and sororities at your campus, set up a meeting and talk to your campus Greek adviser. S/he may be able to best advise you.