It is not difficult to legally change a child's name in Oregon--you do not even need a formal process because Oregon allows you to simply ask people to call your child by the new name. However, most parents will want to go to court to file a formal name change in order to obtain a new birth certificate so their child can obtain government-issued identification in the new name. If you are changing a child's name due to an adoption, you can do that within the adoption petition.
Obtain the legal forms for a name change. Many stationery stores carry legal forms, and you can also find them through online services. These are not forms issued by the state of Oregon, but rather are commercially available. As of 2010, the packet of forms will likely cost between $50 and $60.
Fill out the forms, and double check that you have spelled your child's name as you want it to appear on all legal forms. According to the Oregon State Bar Association, you will need the following forms: petition for change of name, order to give notice to appear and show cause, notice of change of name hearing, affidavit of proof of posting notice of hearing, post order affidavit of posting, change of name decree, and notice of change of name.
Create two copies of each form, and have both parents sign each copy. File the forms at your county courthouse. You will have to pay a filing fee (which varies by county). Ask the clerk about any rules unique to your county, as each county is a little different. You are not required to hire a lawyer, but a local attorney would be able to help you follow all the right procedures.
Sometimes you will have a hearing where the judge will ask you to explain why you want to change your child's name. Your child should attend that hearing with you, if possible. If you are changing your child's name as part of an adoption, you can include the name change in the adoption petition and will not need to file separate name-change forms.
After the judge allows the child's name change, if it is not part of an adoption decree, you will need to post notice of the name change at the courthouse for 14 days. After that, your child's name change will be final and you can apply for a new birth certificate if you wish.