An Illinois affidavit for Service by Publication is a legal document filed in court which states that an individual or entity has made a good faith effort to locate a party or parties to a lawsuit and is unable to do so. It is used when a party to a lawsuit cannot be located, either through a lack of contact information, or an inability to serve the party with the summons and complaint. The affidavit must contain a detailed description of the efforts made to locate the party or parties, and is required when an individual or entity wishes to serve a party or parties by posting a notice of the lawsuit in a designated public newspaper. There are two types of Illinois Affidavit for Service by Publication: 1) Affidavit of Diligent Search; and 2) Affidavit of Publication. The Affidavit of Diligent Search must include information on all efforts made by the person filing the affidavit to locate the party or parties, and must be accompanied by a copy of the notice of publication. The Affidavit of Publication must include information on the publication of the notice, including the name of the newspaper, the date of publication, and a copy of the notice of publication.