Brenda Matthews (NRC Herzberg) ALMA Observations of Debris Disks: A Window into the Diversity of Planetary Systems ALMA has now observed a significant number of debris disks, ranging from those well-studied by earlier facilities to those recently identified. An interesting characteristic of this class of circumstellar disks, those collisionally-generated around young and old stars, is their striking diversity. While the mechanism which generates debris disks is most commonly a collisional cascade acting to return large solid bodies to small dust grains, debris disks are not easily classified into categories by their morphology. ALMA has revealed disks which appear very broad in radial distribution and also many that show confined narrow rings of emission. Most interestingly, ALMA has finally begun to reveal significant numbers of debris disks with evidence of molecular gas emission, including several which are so young that the origin of the molecular gas is difficult to discern: is the gas leftover from a protoplanetary disk or is it, like the dust, second-generation, i.e., the product of collisional processes? These disks essentially bridge the gap between transition and debris disks, revealing the latter to be very much along the continuum of circumstellar disk evolution rather than a class by themselves.