The self-perceived physical health of mothers raising children with developmental delay (DD; N = 116) or typical development (TD; N = 129) was examined across child ages 3-9 years, revealing three main findings. First, mothers of children with DD experienced poorer self-rated physical health than mothers of children with TD at each age. Latent growth curve analyses indicated that mothers in the DD group experienced poorer health from age 3 but that the two groups showed similar growth across ages 3-9 years. Second, cross-lagged panel analyses supported a child-driven pathway in early childhood (ages 3-5) by which early mother-reported child behavior problems predicted poorer maternal health over time, while the reversed, health-driven path was not supported. Third, this cross-lagged path was significantly stronger in the DD group, indicating that behavior problems more strongly impact mothers' health when children have developmental delay than when children have typical development. The health disparity between mothers of children with DD vs. TD stabilized by child age 5 and persisted across early and middle childhood. Early interventions ought to focus on mothers' well-being, both psychological and physical, in addition to child functioning. (Contains 2 tables and 4 figures.)