To help a parent obtain a green card, the eligibility requirements are generally straightforward. As the son or daughter who wants to petition a parent, you must be a U.S. citizen at least 21 years old. Although it gets a bit more complicated, this privilege extends to specific stepparents and adopted sons and daughters. Immigration law defines the parents of U.S. citizens as immediate relatives, and there is no numerical limit on immigrant visas for immediate relatives. Therefore, parents get priority as compared to other preference-based family relationships. The process begins by filing a visa petition for your mother or father. Unfortunately, permanent residents cannot petition a parent for a green card. The best solution is for the permanent resident to naturalize as a U.S. citizen and then submit a petition for the parent.