Crown moulding primarily refers to a decorative row of trim applied where the walls meet the ceiling of a room. It may be narrow or over a foot wide. The style of moulding that is selected, and the colors and finish chosen can define a room, for good or bad. Quite often other architectural details such as fireplaces, doorways or bookcases may be trimmed with matching mouldings.

Often associated with formal room presentations, crown moulding can also be successfully used even in informal cottages. In middle-class homes, dining rooms, dens, bathrooms, living and sleeping areas, creative or subtle mouldings will add to the decorative value.

Crown mouldings may be made from a variety of materials, but are traditionally wood. Extremely ornate mouldings may be cast in plaster, but these are more often found in large public buildings. Complex linear mouldings may be built up from several layers of more simple strips. Other materials such as extruded vinyl or foam are sometimes used. 

Bright or deep wall colors may be tied together and made less overbearing by the use of mouldings and trims, including crown mouldings. It can be possible to use colors which might overwhelm a room and create a striking effect with white mouldings which soften the intense hues.

Different linear surfaces of complex mouldings can be painted in different tones. This creates a striking effect, highlighting light and shadows. Using tones of the same color for this effect can create subtle depth. The use of various colors, including gilding, might be typical of some Victorian style homes. On the other hand, an art deco look, or modern effect, can be created with bold contrasting shades.

A room painted in earthy tones may be trimmed with crown mouldings stained in natural colors. This can add distinctive character to a den or masculine room. If one is careful to choose a light natural finish, the room will not become too dark, and the trim will enhance the richness of the space.

Perhaps the most rich application of crown moulding would be in a room such as a library which is fully paneled in wood. In this case the angles of the moulding serve to add interest. The subtle light and shadow of the layers soften the corners of the room preventing the functionality of shelves and cupboards from becoming stark.

Because of the extra detail that crown mouldings add, they are often combined with other decorative features. Fireplaces may be flanked by columns and mantlepieces which echo the elements of the other mouldings. Window pediments, stairways, or fanlights can also be tied stylistically to the crowns.

Crown moulding makes a statement wherever it is used. As with any decorating plan one must be careful to use the various elements with good taste. The moulding should add to the style of the room without calling attention to itself as separate from the overall effect of the room.