A key to understanding the formation of planetary systems lies in characterizing the transitional phase between the gas-rich primordial disks found around young T Tauri stars and the tenuous, virtually gas-free debris disks around their main-sequence counterparts. High spatial resolution imaging at millimeter wavelengths can provide valuable snapshots of the distribution of gas and dust during the clearing process, opening a window into this elusive phase of evolution and providing clues to the physical mechanisms responsible for disk dissipation. I will describe subarcsecond-scale observations from the Submillimeter Array, the Plateau de Bure Interferometer, and the Very Large Array that resolve inner holes in the gas and dust distributions of disks around young stars. I will discuss how these observations, when combined with other available multiwavelength data, place strong constraints on the physical processes responsible for disk dissipation.