A new method is proposed for probabilistically describing the breakup of reentering space debris. The method provides distributions of breakup altitude, debris area, and casualty area. The process begins with discretization of a reentering body into elements, corresponding largely to body components. Through reentry-heating solutions and applied uncertainties of parameters, probabilities for element separation from the parent body are obtained as a function of altitude, while accounting for ablation and fragmentation. Through additional heating and probabilistic analyses, the population of total fragments is reduced to account for fragments not surviving to ground impact. This leaves surviving-debris-area distributions along the reentry trajectory, which can be directly converted to casualty-area distributions. Finally, through a probabilistic aggregation operation, the casualty-area distributions over altitude are converted to a total-casualty-area distribution. Implementation of this new method is demonstrated for several components of a Delta II 2nd stage rocket body.