Why mix colors when just one will do? It might fly in the face of typical interior design advice, which advocates balance above all things, but sometimes a room that fully embraces a single color can be strangely delightful. Layering the same color in different shades—or a handful of colors in very similar hues—can create a rich, immersive design experience that's as stylish as it is unexpected.
Above: I'm a sucker for lavender, and for velvet, so of course I love this room from Dear Designer, which pairs lavender walls with a purple sofa and purple rug for a luxurious effect.
Blue on blue on blue (and a touch of black) make this dining setup from House & Home unforgettable.
The same effect can work with light colors, too. Notice that in this example from Desire to Inspire, the blue of the couch, the walls, and the drapes are all very similar though slightly different hues, which helps to give the room depth.
Even the mats of the frames match in this room from Neiman Marcus, displaying an admirable dedication to the scheme.
Once you've matched your couch to the walls, why not take it to the next level with artwork, too? Painting bookcases the same color as the wall gives them a built-in look. Image from Skona Hem.
If you love teal, you'll love this space from Urban Outfitters. The dominant teal on the walls and couch makes the blue accents really pop.