<p>Mental health in late childhood and early adolescence reflects both low psychopathology and strong positive resources. This study examined within-person links among subjective well-being (SWB), hope, and depressive symptoms across five annual waves as students progressed from grades 4 to 8 in China (<i>N</i> = 1,128; T1 <i>M</i>_<i>age</i> = 10.35, <i>SD</i> = 0.48; 51.5% were boys and 48.5% were girls; ethnicity was not assessed). Using a random-intercept cross-lagged panel model, we separated stable between-person differences from within-person fluctuations and estimated cross-lagged effects. Results supported an asymmetric cascade: higher SWB predicted subsequent increases in hope, and higher hope predicted later reductions in depressive symptoms; reverse paths were generally non-significant. Two grade-specific exceptions (grade 4 to 5: depression negatively predicted hope; grade 7 to 8: hope predicted SWB) suggested developmental and contextual moderation. Overall, SWB appears to initiate a process that cultivates hope, which then buffers future depressive symptoms, highlighting school-relevant interventions that enhance SWB and build hope in late childhood.</p>