United States
* President: James K. Polk
* Commanding General: Zachary Taylor
* Major Generals: Winfield Scott, John E. Wool, William J. Worth
* Notable Officers: Robert E. Lee, Ulysses S. Grant, George B. McClellan, Jefferson Davis, Stonewall Jackson
Mexico
* President: Antonio López de Santa Anna
* Commanding General: Mariano Arista
* Notable Officers: Pedro de Ampudia, José Joaquín Herrera, Manuel María Lombardini, Nicolás Bravo
Other Participants
* Native American tribes (e.g., Comanche, Apache, Navajo)
* European volunteers (e.g., Irish, German, French)
* Californios (Mexican-Americans in California)