Children experiencing difficulties in reading and math represents an important public health issue, as struggles with reading and math are associated with consequences regarding academic and life success, including but not limited to academic failure and lower socioeconomic status as an adult (Geary, Hoard, Nugent, & Bailey, 2012; Ritchie & Bates, 2013). Highlighting the scope of this problem, a large proportion of U.S. students struggle in reading and math. Startling enough, 20%-25% of fourth-graders fail to reach even partial mastery of grade-level knowledge in reading and math (National Assessment of Educational Progress, 2019). Given the reciprocal influences between reading and math (e.g., Cameron, Kim, Duncan, Becker, & McClelland, 2019) alongside the shared co-occurrence of reading and math difficulties (Landerl & Moll, 2010), it is noteworthy that their development has been mostly studied in isolation of each other (Vanbinst, van Bergen, Ghesquière, & De Smedt, 2020). This is surprising as knowledge on their potential mutual unfolding over time may help inform instruction and types of interventions in both academic outcomes. The aforementioned observation set the foundation for the present study to address the nature of the developmental dynamics between reading and math. The goal of the study was to examine the extent to which reading and math co-develop across elementary grades in academically at-risk children, precisely the key time period for the most rapid reading and math development. We utilized a state-of-the-art approach called latent change