This study explored the dynamics of motivational development across late elementary and early middle school. Using longitudinal data from a cross-section of fifth to seventh-grade students, analyses examined whether parents' and teachers' warm involvement shows unique and/or mediated effects on students' academic engagement and whether engagement feeds back into adults' continued involvement. Parent and teacher involvement each predicted changes in adolescents' engagement; parental involvement also played an indirect role via student-teacher relationships; and students who were more engaged reported that adults responded with increasing levels of involvement. These models provide support for a reciprocal dynamic that could lead to virtuous cycles increasing in both involvement and engagement or to vicious cycles amplifying disaffection and withdrawal of involvement over time. Future studies, using time series or observational data, could further unpack these dynamics, examining processes of transmission, mediators, and effects on the longer-term development of academic engagement.