Hope is a malleable cognitive-motivational skill that helps students identify personal goals and construct routes to achieve them. Hope is sustained through engaging contexts and supportive relationships. We examined cognitive school engagement, teacher support, and peer support during high school (297 students; 9th-11th grade; 45% female; 52% White, 45% Latinx, 3% other) as potential mechanisms in the process of sustaining hope over time, and predicting academic achievement. We hypothesized high school students' hope (time 1; T1) would be indirectly related to subsequent hope (time 2; T2) and achievement (time 3; T3) "via" cognitive school engagement and supports (T2). Significant longitudinal indirect effects emerged from T1 hope to T2 hope "via" T2 cognitive school engagement and peer support, and between T1 hope and T3 achievement "via" T2 cognitive school engagement. Findings highlight the processes that link student hope with achievement and greater hope in the high school context.