It's the trend we've been waiting for ever since our mom stopped letting us leave the house in PJs: It's all about slouchy pants and relaxed-fit tops that feel comfy and look ultra-polished. Think flyaway tanks, trapeze tees, palazzos, gauchos and harem pants, for starters. To wear them just right, practice the rules of proportion—and counter their flow with a fitted blouse or bottom. Or, decide to throw all rules out the window (Sorry, mom!), and double up on the trend—but create balance with extras. Wide-leg pants and a roomy crop top? With a sleek tote and sandals, it works. Sleep on it.