In this episode of the Core Ideas podcast, our introduction to paleolimnology is concluded with a discussion about using indicators preserved in lake sediments to produce environmental reconstructions. We cover why environmental reconstructions are useful, how calibration sets are used to produce transfer functions that are able to transfer knowledge of the modern environment “downcore” and infer the history of an environmental variable from sedimentary assemblages. To round out the discussion, we list off some things to keep in mind, when producing or using environmental reconstructions.