A process server does not have to be licensed in Wisconsin. However, he or she must be authorized by the county court where they are serving. Any adult resident of Wisconsin may deliver an authenticated copy of the summons. He or she may not be a party to the action, and service must be effected with reasonable diligence.

The form of the process depends on the manner of the service. Wisconsin uses four different summonses for four different service regimes. They are 1) personal service with the complaint attached; 2) personal service with no complaint attached; 3) no personal service, complaint served at the same time; and 4) no personal service, complaint not served at the same time.

Personal service is effected by personally serving the summons upon the defendant either within, or outside of, the state of Wisconsin.

If with reasonable diligence the defendant cannot be served, he or she may be served by leaving a copy of the summons at the defendant's usual place of abode in the presence of some competent member of the family at least 14 years of age, who is told the contents thereof, or in the presence of a competent adult, currently residing there, who shall be informed of the contents of the summons, or in a fashion pursuant to the law for the substituted service of summons.

If with reasonable diligence the defendant cannot be served personally or by mail, service may be made by publication of the summons and by mailing. If the defendant's post office address is known or can be ascertained with reasonable diligence, there shall be mailed to the defendant, at or immediately prior to the first publication, a copy of the summons and a copy of the complaint. The mailing may be omitted if the post-office address cannot be ascertained with reasonable diligence.

Service of the summons may be done in a manner specified by any other statute.

Any person may serve any subpoena by exhibiting and reading it to the witness, or by giving the witness a copy thereof, or by leaving such copy at the witness's abode.

A summons served personally or by substituted personal service upon another authorized to accept service is deemed served on the day of service. A summons served by publication is served on the first day of required publication.