It is unknown whether caregivers who perform more caregiving tasks have a greater decline in health from higher stress or less decline because of better health, staying active, or psychological factors. This 1999-2004 US study examined caregiving intensity and 2-year change in performance-based functioning among 901 elderly women from the Caregiver-Study of Osteoporotic Fractures sample. Caregivers were categorized as high (n = 167) or low (n = 166) intensity based on how many activities of daily living they performed for the care recipient. Caregiving intensity status and physical performance score (sum of quartiles of walking pace, grip strength, and chair-stand speed; range, 0-9) were assessed at baseline and at 2 annual follow-up interviews. At baseline, high-intensity caregivers reported the most stress but had the best physical functioning; noncaregivers (n = 568) had the poorest physical functioning (adjusted scores = 5.09 vs. 4.54, P = 0.03). Low-intensity caregivers declined more than noncaregivers over 2 years, but high-intensity caregivers did not (adjusted difference = -0.33, P = 0.07 vs. 0.03, P = 0.89). Among respondents with the same caregiving status at baseline and 1-year interviews, high-intensity caregivers maintained the highest physical performance throughout follow-up. Higher levels of physical performance persisted over 2 years among high-intensity caregivers, which did not support the traditional stress hypothesis.