Prof. Martini is an observational astronomer and instrumentalist, with a focus on the evolution of galaxies and active galactic nuclei (AGN). He has done leading work in constraining the lifetimes of bright quasars, the fueling of AGN, and the demographics of AGN in clusters of galaxies, groups, and the field environment. His recent work has focused on galaxies, and in particular star formation, dust, and environmental processes that affect galaxy evolution in the local universe. He uses an array of multi-wavelength data including X-ray, visible, infrared, submillimeter and radio observations. In addition, Prof. Martini designed and built, in collaboration with the Imaging Sciences Laboratory at Ohio State, the OSMOS and C/KOSMOS instruments, a suite of three similar medium resolution multi-object optical spectrographs for the MDM, CTIO, and Kitt Peak observatories, respectively. He is also the co-chair of the QSO Working Group of the Dark Energy Survey.