In this article we explore students' attitudes towards solidarity, as an aspect of sustainable development (SD), and analyse how students can be described as solidary. Our motive is to obtain better knowledge regarding important preconditions for education for SD. We conducted a quantitative study with 782 responding upper secondary students from 22 Swedish schools. A new scale was designed to measure shared responsibility and pro-environmental behaviour as aspects of solidarity. Background variables were sex, parents' level of engagement, geographical knowledge, future orientation, biospheric values and environmental educational tradition. The descriptive results confirm previously found gender differences including women showing considerably higher scores on the three subscales measuring solidarity. The correlation analysis shows significant and moderate correlations between solidarity and biospheric values which is also consistent with previous research. More pioneering is that future orientation correlates significantly and relatively strongly with solidarity. The regression analysis furthermore shows that future orientation is a significant predictor for solidarity. More research is needed before we can draw unequivocal conclusions regarding this relation but meanwhile we interpret the findings as an insistent reminder to highlight the future dimension in education for SD.