Washington Petition To Decide Parentage is a legal document used to determine the legal parent of a child in the state of Washington. This document is usually used when the mother and father are not married. Through this petition, the court can decide who is the legal parent of the child and can then enter an appropriate judgment for the parent-child relationship. There are two types of Washington Petition To Decide Parentage: one for married couples and one for unmarried couples. The petition for married couples is called the Establish Parent-Child Relationship Petition, while the petition for unmarried couples is called the Parentage Petition. The petitioner must provide information on the identity of the child, the parents, and any other relevant information that will help the court make its decision. Once the petition is filed, the court will review the evidence and determine the legal parent-child relationship.