San Gabriel was one of five missions already established in Alta California at the time of the Anza Expedition. The others were San Diego, San Antonio de los Robles, San Luís Obispo de Tolosa, and San Carlos Borromeo del Carmelo. The establishment of Mission San Juan Capistrano had just begun when the San Diego Indian uprising occurred and the missionaries were called back until things settled down. Thus, it was not up and running when Anza arrived on the scene.
San Gabriel means "Saint Gabriel" in English.