ABSTRACT: Western Ireland is ideally situated to receive maritime precipitation that has uncomplicated trajectory histories. Biota in Irish lakes therefore have the potential to divulge temperature and precipitation records for the Holocene. Blanket bog cores adjacent to Lough Corrib contain abundant ostracoda whose calcite shells were analyzed for stable oxygen and carbon isotope values. The earliest Holocene sediments are characterized by the cool water, oligotrophic ostracode Limnocytherina sanctipatricii that displays relatively high δ18O and δ13C values, indicative of cool, arid conditions. Middle Holocene sediments are characterized by cool, humid conditions differentiated by abundant Metacypris cordata that thrived on productive carbonate benches surrounding the lake perimeter. Relatively low oxygen isotope values suggest cool, wet conditions. Carbon isotope values are relatively low as DIC was dominated by terrestrial organic matter. Late Holocene warm, humid conditions are differentiated by decreased Metacypris cordata abundance and relatively high δ18O values in response to increased atmospheric warmth and increased rates of vegetative production. Possible climate excursions include the 8.2 kyr cold event and the Middle Holocene Thermal Maximum.