I've been through this process (501Â©(3)) before, and while I can't remember all the details, I do recall that it required a good deal of hoop-jumping. Â Here's the basics from the IRS's website:
To be tax-exempt as an organization described in IRC Section 501Â©(3) of the Code, an organization must be organized and operated exclusively for one or more of the purposes set forth in IRC Section 501Â©(3) and none of the earnings of the organization may inure to any private shareholder or individual. In addition, it may not attempt to influence legislation as a substantial part of its activities and it may not participate at all in campaign activity for or against political candidates. . . The exempt purposes set forth in IRC Section 501Â©(3) are charitable, religious, educational, scientific, literary, testing for public safety, fostering national or international amateur sports competition, and the prevention of cruelty to children or animals. The term charitable is used in its generally accepted legal sense and includes relief of the poor, the distressed, or the underprivileged; advancement of religion; advancement of education or science; erection or maintenance of public buildings, monuments, or works; lessening the burdens of government; lessening of neighborhood tensions; elimination of prejudice and discrimination; defense of human and civil rights secured by law; and combating community deterioration and juvenile delinquency.
If you want more details, here's the link