Abstract: Disclosed are various embodiments of a collapsible containment bag configured to retain a collection of hazardous materials. In one embodiment, the containment bag includes a non-porous liner, a plastic sheeting, and a bag frame. The containment bag may be in a collapsed state initially and later expand for use at the site of an environmental spill. The containment bag may be expanded from the collapsed state through a series of actions that may include pivoting a portion of the containment bag about an edge and pulling opposing sides of the containment bag away from the center of the containment bag.