Coalition governance divides policymaking influence across multiple parties, making it challenging for voters to accurately attribute responsibility for outcomes. We argue that many voters overcome this challenge by inferring parties’ policymaking influence using a simple heuristic model that integrates a number of readily available and cheaply obtained informational cues about parties (e.g., their roles in government and legislative seat shares) — while ignoring other cues that, while predictive of real-world influence, are not suitable for heuristic inference (e.g., median party status and voting power). Using original data from seven surveys in five countries, we show that voters’ attributions of parties’ policymaking influence are consistent with our proposed inferential strategy. Our findings suggest that while voters certainly have blind spots that cause them to misattribute policy responsibility in some situations, on the whole their attributions of policymaking influence are quite sensible.