I study the formation and evolution of galaxies through cosmic time. My current focus has been the evolution of galaxies during the first two billion years of the universe (z~3-10). I conduct my studies using data from the Hubble Space Telescope, the Spitzer Space Telescope, and large ground-based telescopes like Keck, Subaru, or VLT. My work has primarily centered on the determination of the UV LFs from z~8 to z~4, but I have also been investigating the sizes, surface brightnesses, UV colours, dust content, and correlation properties of galaxies at these early times.