Purpose: We examined whether the timing of when a person experienced the loss of a parent to incarceration was significantly associated with allostatic load, a multisystem index of biological dysregulation. Methods: Data were drawn from waves I and IV of National Longitudinal Study of Adolescent to Adult Health, a nationally representative sample of adolescents in 1994. The final analytic sample was restricted to responses with valid responses and valid sampling weights (n = 13,365). Survey-corrected negative binomial regressions were used to assess relationships between timings of parental incarceration and allostatic load. Results: Compared with respondents with no history of parent incarceration, reporting the incarceration of a parent in childhood was associated with higher allostatic load scores, whereas losing a parent to incarceration in adulthood was associated with significantly lower allostatic load scores. Conclusions: The physiological consequences of parental incarceration are associated with the developmental period in which the incarceration occurred. The risk of biological dysregulation may be greatest among those who experience the loss of a parent to incarceration in childhood.