I am primarily interested in cosmology and galaxy formation and evolution using both observational and theoretical approaches. Recently I was one of the leaders of the Supernova Legacy Survey which found that the dark energy was constant in time to a precision of better than 10%, consistent with Einstein’s cosmological constant. I am also interested in star streams as indicators of the dark matter substructure of the Milky Way halo. I was the Thirty Meter Telescope’s Canadian Project Director 2003-17.