The El Niño Southern Oscillation (ENSO) is the largest source of interannual climate variability on Earth and influences climate worldwide via teleconnections. ENSO variability during much of the 20th century is well documented through instrumental and proxy climate records. Prior to the 20th century, records from key ENSO sensitive regions and with the appropriate resolution are sparse. We present a monthly resolved coral Sr/Ca-SST record from Vanuatu with the goal of enhancing our understanding of the natural variability of the ENSO system during the late 18th and 19th centuries. This record fills in critical missing sections of the coral-based ENSO record from the early 19th century and earlier. The chronology of the core, extracted from a live Porites coral at Sabine Bank, Vanuatu (~166° E, 16° S) in 2007, was established by annual band counting. Calibration of the Sr/Ca-SST proxy is enhanced by the existence of an in situ thermistor dataset. These in situ data are used to scale SST data from gridded SST data products. ENSO warm phase events in the 20th century, as identified in instrumental records, are well recorded in our coral Sr/Ca-SST record. We use this relationship to established criteria for defining ENSO warm phase events in the pre-20th century portion of our coral record. We identify several ENSO warm phase events in the 19th century, some with SST anomalies comparable to those of the events of '82/'83 and '97/'98. Many of the ENSO warm phase events identified in our coral records are consistent in timing with those noted from the historical record.