Developmental disabilities are a heterogenous group of disorders characterized by impairments in physical functioning, learning, language, behavior, and self-care (Zablotsky et al., 2019). Parenting a child with a developmental disability can be a profound source of stress, particularly for mothers. This atypical parenting experience can begin with the birth of the child, or soon thereafter, and continues over the life course, often extending six decades or more. However, there is limited research on the impact of this parenting role across the full adult life course - from mothers' early years of parenting through older age. Here we draw on data from two separate studies, one a national study of mothers of children with a range of developmental conditions (n = 96) and the other a community study of mothers of children with autism (n = 391). We used an accelerated longitudinal design to estimate mothers' trajectories of health, mental health, and cognitive functioning beginning in their 20s and extending until their 80s or beyond, and conducted a series of cohort and sensitivity analyses. Together, the results of analyses of these two studies revealed very similar patterns across a number of important outcomes. The inclusion in one of the studies of a nationally representative comparison group of mothers whose children did not have disabilities (n = 1,181) indicated that after around age 65, aging in mothers of children with developmental disabilities differed from the norm, suggesting the 'wear-and-tear' effects of this common form of stressful parenting.