The study of microbiologically influenced corrosion (MIC) has progressed from phenomenological case histories to a mature interdisciplinary science including electrochemical, metallurgical, surface analytical, microbiological, biotechnological and biophysical techniques. With microelectrodes and gene probes it is now possible to measure interfacial dissolved oxygen, dissolved sulfide and pH and to determine microbial species responsible for localized chemistry. Biofilms can be tailored to contain consortia of specific microorganisms and naturally-occurring biofilms can be dissected into cellular and extracellular constituents. Scanning vibrating electrodes can be used to map the distribution of current density. Electrochemical impedance spectroscopy and electrochemical noise analysis techniques have been developed to non-destructively evaluate MIC. The development of environmental scanning electron, atomic force, and laser confocal microscopy makes it possible to image cells on surfaces and to accurately determine the spatial relationship between microorganisms and localized phenomena. Transport of nutrients through biofilms have been modeled using optical density measurements to precisely locate the water/biofilm interface and nuclear magnetic resonance imaging to visualize flow characteristics near surfaces colonized with microorganisms. The ways in which new techniques can be used to understand fundamental mechanisms and to discriminate MIC will be discussed.