An Illinois Petition for Name Change (adult) is a legal document that is used to change the name of an adult in the state of Illinois. There are two types of name change petitions for adults in Illinois: a Petition for Change of Name due to Marriage and a Petition for Change of Name not due to Marriage. The Petition for Change of Name due to Marriage is used when an adult wishes to change their name to that of their spouse or partner after getting married or entering into a civil union. The Petition for Change of Name not due to Marriage can be used when an adult wishes to change their name for any other reason, such as personal preference or to reflect a gender transition. Both types of petitions require applicants to provide personal information, such as their current name, address, date of birth, and Social Security number. Applicants must also provide a reason for the name change and must include the signature of at least one witness. The petition must be submitted to the local circuit court in the applicant’s county of residence.