Abstract: Debris disks are more massive analogs of our solar system's Kuiper Belt, and they trace the final assembly stages of planetary systems. The Atacama Large Millimeter/submillimeter Array (ALMA) has provided sensitive, high-resolution views of millimeter-size dust and molecular gas that allow us to trace the dynamics and chemistry of this pivotal planet formation phase. I will describe several recent observations of gas and dust in debris disks with ALMA, including a new large program that will reveal how disk structures like rings and gaps evolve as the star settles onto the main sequence.