He is the author of roughly 100 papers in the professional literature and is a frequent user of the Hubble Space Telescope, Canada-France-Hawaii Telescope, the Chandra X-ray Observatory, the Spitzer Space Telescope, the W.O. Keck Observatory and Gemini Telescopes, and the Very Large Telescope in Chile.

His research interests include the study of dark matter, galaxy evolution, supermassive black holes, star clusters and galactic nuclei. He was the principal investigator of the ACS Virgo Cluster Survey (ACSVCS), which used the Hubble Space Telescope to study the properties of galaxies in the nearby Virgo Cluster. He is a core member of the Next Generation Virgo Cluster Survey (NGVS) that is now underway at the Canada-France-Hawaii Telescope. He is the lead scientist for two large projects that are presently under development: the Cosmological Advanced Survey Telescope for Optical and uv Research (CASTOR) and the Next Generation Canada-France-Hawaii Telescope (ngCFHT).