Short answer. Section 1 of Rule 7 requires the caption to set forth the court's name, the title of the action (indicating the parties' names), and the docket number if one has been assigned. All parties must be named in the original complaint or petition.
What the law says
The caption sets forth the name of the court, the title of the action, and the docket number if assigned. The title of the action indicates the names of the parties. They shall all be named in the original complaint or petition; but in subsequent pleadings, it shall be sufficient if the name of the first party on each side be stated with an appropriate indication when there are other parties.
Rule 7, Section 1 — Caption. Read the full provision →
The three components of a caption
Section 1 breaks the caption down into specific required elements: the name of the court where the case is filed, the title of the action, and the docket number, if one has already been assigned at the time of filing. Together these identify, at a glance, exactly where the case is pending, who the parties are, and (once assigned) the case's official tracking number in that court.
Naming the parties in the title
The title of the action is where the names of the parties appear, and Section 1 requires that all parties be named in the original complaint or petition — the very first pleading that initiates the case. This ensures a complete, accurate record from the outset of exactly who is suing and being sued, which matters later when the court, the parties, and anyone reviewing the case file needs to identify everyone bound by the eventual judgment.
A shortcut for later pleadings
Once the full party list is established in the original complaint or petition, Section 1 relaxes the naming requirement for subsequent pleadings: it is sufficient if the name of the first party on each side is stated, with an appropriate indication when there are other parties. Each party's respective participation in the case must still be indicated, but the caption itself does not need to relist every single party by name in every filing that follows.
Why these three elements together matter
The court's name, the case title, and the docket number work together as a kind of address for the case — anyone handling the pleading, from the clerk's office to opposing counsel, can immediately tell where the case is pending, who the parties are, and how to locate it in the court's own records once a docket number has been assigned. A caption missing any of these elements makes routine case administration harder for everyone involved.