A window, which may be a casement window, includes an opening control mechanism for limiting the amount that the sash of the window can be opened to control ventilation and as a child safety feature. In one configuration, the opening control mechanism includes a frame track and release assembly attached to the window frame and a sash arm assembly including an articulating sash arm attached to the sash of the window. The frame track and release assembly has a track and a roller on one end of the sash arm rides along the track as the window sash begins to open. At the end of the track, the roller engages and is restrained by a release arm or stop thereby preventing the sash from being opened further. A lever or a button operatively coupled to the release arm is disposed inside the dwelling and inside an insect screen of the window. The lever can be slid sideways and then pulled back in two distinct motions to release the roller to allow the sash to be opened beyond its restrained position. The button can be exposed by moving a hingable cover from over the button and the button pressed to release the roller. The sash arm and track re-engage automatically when the window sash is closed.