The Illinois Joint Petition to Establish Parent and Child Relationship is a legal document filed in state court that seeks to legally establish the parent-child relationship between a parent and a child. It is typically used in cases where the child is born out of wedlock or when the biological parent is unknown. There are two types of Illinois Joint Petition to Establish Parent and Child Relationship: a voluntary joint petition, and an involuntary joint petition. A voluntary joint petition is typically filed by both the biological parent and the alleged parent, and is used to establish paternity and parental rights in cases where the biological parent is not known. An involuntary joint petition is typically filed by the state or a third party, and is used to establish paternity and parental rights when the alleged parent is unwilling or unable to voluntarily file a joint petition. In either case, the Illinois Joint Petition to Establish Parent and Child Relationship must be signed by both the alleged parent and the biological parent, and must be accompanied by a court order establishing the parent-child relationship.