Who can I sponsor in RPI status?

Under the provisions of the Border Security, Economic Opportunity, and Immigration Modernization Act of 2013 (BSEOIM), an immigrant granted the Registered Provisional Immigrant (RPI) legal status cannot sponsor a family member outside the United States.  In fact there is no provision for sponsorship, except that the principal applicant can file applications on behalf of spouse and children as derivatives as long as they are in the United States illegally.  However, once the RPI visa is converted to a green card (10 years for most immigrants and 5 years for DREAMers), they can sponsor spouse and children.  Once you become a naturalized US citizen, you can even sponsor your parents, who can then, in turn, sponsor their other children.