The Philippine Department was a regular United States Army organization whose mission was to defend the Philippine Islands and train the Philippine Army. On 9 April 1942, during World War II, the organization surrendered to the Japanese. The department and its sub-units were predominantly under the command of American officers, including an American general, while the majority of the troops were enlisted Filipinos, known as the Philippine Scouts (PS). The primary force of this department was the Philippine Division. Of the 22,532 troops, 10,473 were members of the Philippine Division itself.

The Philippine Scouts (Filipino: Maghahanap ng Pilipinas/Hukbong Maghahanap ng Pilipinas) was a military organization of the United States Army from 1901 until after the end of World War II. These troops were generally Filipinos and Filipino-Americans assigned to the United States Army Philippine Department, under the command of American commissioned officers (though a handful of Filipino Americans received commissions from the United States Military Academy). Philippine Scout units were given the suffix "(PS)", to distinguish them from other U.S. Army units.