The past ten years have seen explosive growth in “non-traditional” stable isotope geochemistry, particularly of transition metals, largely as a result of analytical innovations in mass spectrometry. Mass dependent variations in isotopic composition are now being studied actively for approximately twenty elements in addition to the “traditional” H, C, N, O and S, giving rise to a new geochemical subdiscipline. We are using multiple-collector inductively coupled plasma mass spectrometry to develop and apply these novel systems, particularly Fe and Mo, as well as to carry out research with well-established isotope tracers such as Sr isotopes. These efforts focus primarily on using isotopic techniques to study biological and chemical processes at the Earth's surface and their change with time. In addition to basic studies of isotope fractionation mechanisms, we are investigating the use of metal stable isotopes as paleoredox proxies and as probes of microbe-mineral interactions. Additionally, we are interested in the application of isotopic methods outside of geosciences, such as in anthropology and medicine.