Objectives: This study examines the factors associated with caregiver strain experienced by informal caregivers of older people, using data from Ireland. Methods: The analysis is based on a sample of 1394 informal caregivers obtained from Ireland’s Quarterly National Household Survey (2009). The Caregiver Strain Index is used to measure caregiver strain on a scale from 0 to 13. The analysis focuses on estimating the association between caregiving activities (measured using Activities of Daily Living) and caregiver strain, using multivariate regression analysis. Results: Overall, 60% of informal caregivers report feeling strained. The results suggest that different types of caregiving assistance are associated with increasing caregiver strain, in line with Pearlin’s conceptual model of Stress Process theory and Process Utility theory of informal care. Female caregivers have significantly higher levels of strain. Moreover, caregiver strain amongst co-residential caregivers is 0.8 points higher compared to those who are non-resident. Conversely, caregivers over 65 years are less prone to strain than younger caregivers. The condition of the dependent is also a statistically significant factor: caring for someone with a physical condition, a mental condition or both a physical and mental condition, increases caregiver strain. Conclusions: As Ireland and Europe’s populations are ‘greying’, sustainable systems and supports need to be designed to meet demand for care that limit strain for caregivers. In doing so, policymakers and their advisors need to better understand the impact of informal caring on caregivers.