A clamp for engaging a structure flange includes a clamp body having a slot between a pair of body sections, a spring clip on the clamp body that extends into the slot, and a pair of screws threadedly engaged with the clamp body. The spring clip holds a structure flange in place when the clamp is placed on a structure flange, with the flange in the slot. This allows the installer to tighten the screws to engage the flange, without having to simultaneously hold the clamp in place. The screws may bite into the flange, providing a more secure coupling between the clamp and the structure flange. The clamp may be used to mount a variety of objects, such as sway braces for seismic bracing.