Magnetic susceptibility (MS) is a tool frequently used by geologists on sediments or rocks to perform correlations and sea-level or climatic reconstructions. Applied measurements are made on unoriented, bulk samples and bulk MS is mostly influenced by the magnetic mineral content of the rock and often interpreted as influenced by detrital inputs. Magnetic data acquisition is fast and straightforward and this allows the high-resolution sampling needed for palaeoclimatic research (e.g. spectral analysis). However, the link with detrital inputs is not always preserved and the impact of diagenesis on the final MS signal can blur primary information. This volume includes contributions dealing with the origin of the magnetic minerals, and the application of MS as a palaeoenvironmental or palaeoclimatic proxy and also as a tool to provide astronomical calibration in order to improve the chronology of selected time intervals.