This study examined whether children’s difficulties with stage-salient tasks served as an explanatory mechanism in the pathway between their insecurity in the interparental relationship and their disruptive behavior problems. Using a multimethod, multi-informant design, 201 two-year-old children and their mothers participated in 3 annual measurement occasions. Structural equation modeling analyses indicated that coder ratings of children’s insecure responses to interparental conflict from a maternal interview predicted observer ratings of their difficulties with stage-salient tasks (i.e., emotion regulation, autonomy, resourceful problem solving) 1 year later after controlling for initial stage-salient task performance. Stage-salient task difficulties, in turn, predicted experimenter reports of children's behavior problems 1 year later. Associations remained robust in the broader context of other pathways hypothesized in prevailing developmental cascade models. (Contains 2 figures and 1 table.)