A casement window opening control device including a sash sub-assembly and a frame sub-assembly. The device is self-locating by aligning the bottom end of each sub-assembly with physical features of the window. This saves time and effort in installation by not requiring any measurements to ensure that an engaging feature of the limiting arm of the device is aligned with an engaging feature of the frame sub-assembly so that the device properly reengages upon closing of the sash after release. Also, operation of the release of the travel limiting arm is intuitive, requiring only pressing in on a latch button and sliding it upwardly to effect release.