This paper aims to unite three distinct literatures in considering how siblings may exacerbate life course disparities. First, recent calls to expand the one-parent one-offspring model of intergenerational inequality have been met primarily by extending analyses vertically, to a three-generation model that incorporates grandparents. To more fully understand how complex intra-familial dynamics contribute to the transmission of (dis)advantage, however, a nascent literature suggests that we must incorporate siblings into the theoretical and analytic framework. Second, Torche (2015, p. 346) laments that existing literature reveals “very little about causal processes and mechanisms for the persistence of advantage” and urges researchers to start “moving beyond these specific factors to assess how institutional contexts shape intergenerational opportunity”. A robust collection of research illuminates the consequences of criminal justice contact for youth, but has developed largely independently of the scholarship on intergenerational transmission. And third, a spirited literature in cultural sociology investigates children’s own expectations and aspirations for the future—yet little contemporary work scrutinizes parents’ expectations and aspirations for their children. Therefore, in this work in progress, I expand the familial transmission of inequality model to consider how sibling criminal justice system impact children both directly and indirectly (via their influence on parent expectations and aspirations). Using data from the Project on Human Development in Chicago Neighborhoods (PHDCN), my initial results suggest fairly large deleterious effects of sibling troubles on parent expectations and aspirations, and these effects seem to be concentrated primarily among focal children who have higher levels of behavioral issues.