Shield: From the Provincial Seal of Isabela where the town is located.
Rising Sun: New hope that enlightens on-going development of San Guiilermo.
Mountains: Parts of the Municipality as rolling terrain of the Sierra Madre Mountain Range.
1967: Year when Municipality of San Guillermo was created under Republic Act No. 4906.
Logs & Tree: Town's thick and virgin forest which gives additional income to the Municipality.
Corn and Banana: Major agricultural crops and biggest production for commercial purposes.
Wide Road: Road network linking remote barrios to other nearby municipalities.