Using two waves of longitudinal data, we utilized the family stress model of economic hardship to test whether family socioeconomic status is related to adolescent adjustment (substance use and academic achievement) through parental knowledge and adolescent self-regulation (behavioral self-control and delay discounting). Participants included 220 adolescent (55% male, X-bar[subscript age] = 13 years at Wave 1, X-bar[subscript age] = 15 years at Wave 2) and primary caregiver dyads. Results of Structural Equation Modeling revealed significant three-path mediation effects such that low family socioeconomic status at Wave 1 is associated with low parental knowledge at Wave 1, which in turn was related to low academic performance and high substance use at Wave 2 mediated through low adolescent behavioral self-control at Wave 2. The results illustrate how parental knowledge, influenced by family economic status, may play an important role in the development of adolescent behavioral self-control and adjustment.