While previous research shows that environmental policy attitudes depend on trust in government, existing studies have either focused exclusively on trust in politicians and democratic institutions (political trust) or conflated such measures with trust in a wider range of impartial government institutions and actors. In this study, we distinguish between trust in partial institutions that enact laws and policies on the one hand, and trust in impartial institutions that exercise government authority and enforce policies on the other, and systematically analyse their respective influence on climate policy preferences. In addition to investigating the direct influences of trust, we also focus on how trust in government institutions moderates the relationship between climate change concern and climate policy attitudes cross-nationally. Using European Social Survey data from 2016, we demonstrate that individual-level trust in both partial and impartial government institutions constitutes an important determinant of climate policy attitudes. Moreover, while we find no evidence of direct effects of trust at the country level, we demonstrate that individuals who are concerned about climate change are more likely to hold positive attitudes towards climate policies in high-trust countries, particularly where trust in impartial institutions such as the legal system and the police is high. Key policy insights. Individuals' tendency to favour climate policies depends on their trust in both partial government institutions that enact policies (e.g. parliament, politicians) and impartial institutions that enforce these policies (e.g. legal system, police).. At the country level, trust in impartial institutions plays a particularly crucial role for the translation of individuals' climate change concern into support for climate policies.. A climate policy platform with broad public support not only relies on a trustworthy political system that enacts sound climate policies, but also on well-functioning and trustworthy government institutions that ultimately enforce these policies.