1. Visit the Washington State Office of the Superintendent of Public Instruction (OSPI) website.
2. Click on the "Students and Families" tab.
3. Under the "High School Diplomas" section, click on the "Request a Duplicate High School Diploma" link.
4. Fill out the online form and submit it.
5. You will need to provide the following information:
* Your full name
* Your date of birth
* Your Social Security number
* The name of the high school you attended
* The date you graduated
* Your current mailing address
6. You will also need to pay a fee of $15.00.
7. Once your request has been processed, you will receive a copy of your high school diploma by mail.