Student understanding of climate change is an active and growing area of research, but little research has documented undergraduate students' knowledge about the biotic impacts of climate change. Here, we address this literature gap by presenting the Inventory of Biotic Climate Literacy (IBCL), a concept inventory developed to assess undergraduate biology student knowledge of how climate change impacts living things. We developed the IBCL through literature review, student and expert interviews, student field tests, and expert review. We implemented two large nationwide field tests and conducted multiple psychometric analyses on these datasets. These analyses resulted in a final tool of 30 items measuring 16 constructs related to the biotic impacts of climate change. We discovered that the final IBCL does not represent a single, simple construct but rather the complicated and interactive concepts that comprise this topic. We suggest that sum scores are still a valuable measure, as certain groups (upperclassmen and politically liberal individuals) scored significantly higher. We also found value in analyzing individual student performance on the IBCL by developing student profiles. The IBCL represents an important tool in assessing student understanding of the complex and growing problem of climate change and its impact on the living world.