The importance of knowledge for lay people's climate change concerns has been questioned in recent years, as it had been suggested that cultural values are stronger predictors of concern about climate change than knowledge. Studies that simultaneously measured knowledge related to climate change and cultural values have, however, been missing. We conducted a mail survey in the German-speaking part of Switzerland (N = 1,065). Results suggested that cultural worldviews and climate-related knowledge were significantly related with people's concern about climate change. Also, cultural worldviews and climate-relevant knowledge appeared important for people's willingness to change behaviors and to accept climate change policies. In addition, different types of knowledge were found to have different impacts on people's concern about climate change, their willingness to change behaviors, and their acceptance of policies about climate change. Specifically, causal knowledge significantly increased concern about climate change and willingness to support climate-friendly policies. We therefore concluded that risk communication should focus on causal knowledge, provided this knowledge does not threaten cultural values.