Room-darkening window treatments are almost always requested in bedrooms; however, other needs might include rooms with collectible art, books or antiques, or theatre-style media rooms.

There is a significant difference between window treatments that are "room-darkening" and that are "blackout." Room-darkening allows for a tranquil, shaded ambience in the room with very minimal light. Blackout quality indicates that there is no light allowed in the room at all.

Many hard window treatments, i.e. shades and blinds, may have either a room-darkening or blackout capability. This is generally achieved by choosing a privacy liner or "no-holes" option. Honeycomb shades have varying opacities from semi-sheer to opaque as well as a blackout quality that is achieved with a light-blocking coating inside the cells of the shade. Blackout roller shades are one of the most popular blackout options.

Draperies and valances can be lined and interlined with various styles of linings to achieve different degrees of darkness within the room. Thermal linings can allow solar and heat protection without completely blocking all light within the room while blackout linings create "hotel-style" darkness. Drapery side panels are frequently used in combination with hard window treatments to control light leakage that occurs at the sides of shades mounted inside the window opening.

Below is a chart listing most window treatment options and the effectiveness of each as either a room-darkening or blackout option.