File a petition for a change of name with a court of original jurisdiction where you live, which is usually a district or family court. Every state has different requirements that you need to include in your petition. In general, you will need to include your name, your address, the child's current name, the requested name, the name and address of the other parent and your legal grounds for the name change. Pay any required fees.
Serve the petition on the other parent according to the rules for service of process in your state. The other parent usually must be notified and may have the right to contest your request.
Follow all interim orders of the court. In different states, judges will require that you take different steps. In some states, a guardian ad litem might be appointed to act as an attorney for the child or to represent the best interests of the child. Other orders may include notifying other family members or posting a bond.
Ask the court to schedule a hearing on your request when you have fulfilled all of the court's interim orders. Different courts have different ways to request hearings. Ask the clerk of the court for the rules in your jurisdiction.
Go to your hearing at the scheduled date and time. You will have the opportunity to state your reasons for wanting your child's last name changed. Focus on reasons that the change is in the best interests of child, as that is the legal standard for your request.
File for an amended birth certificate with the state department of vital records in the state in which the child was born, if the judge grants you an order changing the child's last name.
File a new application for a Social Security card on the child's behalf. Include a certified copy of the court order granting the name change with your application.