A double hung window having a tiltable sash includes a sash brake for preventing movement of the sash along the jambs while in the tilted position. The preferred sash includes respective tongues extending along the stiles that are configured for reception in corresponding channels in the jambs for slidably mounting the sash and providing a seal between the stiles and window frame. The preferred brake elements each include a base configured for fitting within a groove of a respective tongue and a brake shoe that extends into the channel. Each shoe has a length greater than the width of channel so that when the sash is tilted, the shoe engages the channel side walls to provide braking against movement while in the tilted position.