Supplemental data for the manuscript entitled "Constraining the decline of the lunar dynamo field at ? 3.1 Ga through paleomagnetic analysis of Apollo 12 mare basalts" by Strauss et al. (submitted 2020). This dataset includes: - Ar-Ar data following the reporting guidelines of Renne et al. (2009) - Paleomagnetism data compatible with PaleoMag software - Microprobe measurement data and text