This research examined how parenting adults with developmental disabilities affects parental well-being beyond midlife and into old age. Parents of adults with developmental disabilities (n = 249) and parents of adults without disabilities (n = 9,016), studied in their early 50s and mid-60s, were longitudinally tracked into their early 70s. Compared to parents of adults without disabilities, parents of adults with disabilities showed a pattern of normative functioning in their 50s, followed by poorer well-being in their mid-60s, and further declines in health and well-being into the early 70s. Aging parents who co-resided with their adult child with disabilities were particularly vulnerable, experiencing a steeper increase in depressive symptoms and body mass index (BMI) than parents whose child with disabilities lived away from home.