Climate change skepticism (CCS) is a significant impediment to sustainable behavior. An in-depth understanding of CCS is therefore essential. However, existing measures vary considerably. In this paper, we address the differences and limitations of existing measures of CCS and present a new measure. In three studies (n = 534; n = 352; n = 252), we examined the factor structure, test-retest reliability, and associations with intentions for sustainable behaviors, psychological resistance to change, and dispositional tendencies for motivated reasoning. The resulting climate change skepticism questionnaire (CCS-Q) is a 12-item scale that assesses four dimensions of CCS: trend, attribution, impact, and response skepticism. The CCS-Q combines expressions of doubt or uncertainty with denial. The studies we conducted support our four-dimensional structure and test-retest reliability was good. Furthermore, CCS-Q scores were negatively related to intentions for sustainable behavior and positively related to resistance to change. We did not find any association with motivated reasoning. Overall, the new CCS-Q offers a reliable and valid measure for CCS.