Washington Return of Service (ROS) is a process used by Washington State courts to serve legal documents to defendants in a legal action. It is the responsibility of the plaintiff or petitioner to arrange for the Return of Service, which is usually done through a process server. Depending on the type of legal action, different types of Washington Return of Service may be required. The two main types of Washington Return of Service are Personal Service and Service by Mail. Personal Service requires that the legal document be delivered to the defendant in person by a process server. The process server must provide proof of delivery, typically through a signed and dated affidavit. Service by Mail requires that the legal document be mailed to the defendant and the plaintiff or petitioner must provide proof of delivery, typically through a signed and dated certificate of mailing or green card. Washington Return of Service is an important part of the legal process and is necessary for a plaintiff or petitioner to move forward with their case.