This paper examines two important procedural institutes in administrative judicial disputes: the joinder of claims and the joinder of parties. These institutes play a significant role due to the complexity of legal-civil relations between public administration and individuals, where issues not resolved through administrative channels often involve multiple parties and different claims. • Joinder of Claims involves presenting two or more claims by the plaintiff in a single lawsuit, where the same procedure is followed for all claims. • Joinder of Parties involves cases where several people are involved as plaintiffs or defendants. Both institutes make civil procedures and the law on administrative courts more complex, requiring greater professionalism from the court due to the need to handle multiple pieces of evidence and hear numerous witnesses and experts. The paper also explores relevant principles and terms, including the concepts of objective and subjective joinder of claims, as well as the importance of the principle of economy.