| San Ildefonso | |
| Settlement Type: | Municipality |
| Pushpin Map: | El Salvador |
| Pushpin Label Position: | bottom |
| Pushpin Mapsize: | 300 |
| Pushpin Map Caption: | Location in El Salvador |
| Subdivision Type: | Country |
| Subdivision Name: |  El Salvador |
| Subdivision Type1: | Department |
| Subdivision Name1: | San Vicente Department |
| Unit Pref: | Imperial |
| Area Total Km2: | 136.37 |
| Population As Of: | 2001 |
| Population Total: | 10015 |
| Coordinates: | 13.7°N -122°W |
| Elevation M: | 205 |
San Ildefonso is a municipality in the San Vicente department of El Salvador.