Objectives: To examine the association between informal caregiving and caregiver work performance. Method: A systematized review of the literature. Results: We found that caregiving has an adverse impact on work performance: caregivers experience substantial work disruptions and negative work performance outcomes, and these findings were consistent across measures. Our synthesis suggests that caregivers miss a significant amount of work and have reductions in productivity due to their caregiving responsibilities. However, significant methodological limitations with the reviewed studies make systematic interpretations and causal determinations challenging. Discussion: Examining the effect of caregiving on work performance is critical to better understand the full impact of caregiving, especially as demand for caregivers increases as the population ages. This comprehensive review suggests that caregiving has a significant negative impact on work performance, although methodological challenges remain in this area of science. These findings should inform both public policy development and workplace benefits design.