Once upon a time, the root beer float was an innocent drink, sipped on burger dates or at the soda fountain. But there's a new generation of the classics that are boozy, rich and for adults only.

CommonWealth Chef Jamie Leeds pours Young's Double-Chocolate Stout as the base for her gastropub's malty float (pictured; $6). Coffee ice cream brightens the beer's chocolate notes and rounds out the finish. 1400 Irving St. NW; 202-265-1400 or commonwealthgastropub.com

Restaurant 3 Brewed with milk sugar, the Duck-Rabbit's Milk Stout has a sweet, toffee finish that tastes like it was meant to mingle with ice cream. Order it with the standard scoop of vanilla ice cream ($7) or up the ante with house-made maple bacon ice cream. 2950 Clarendon Blvd., Arlington; 703-524-4440 or restaurantthree.com

R.F.D. With over 300 bottles and 30 beers on tap, this Penn Quarter bar takes its hops offerings seriously serving two different beer-float ($8) combinations, both made with vanilla ice cream. The chocolate stout float is a mellow, creamy dessert, and the raspberry-based St. Louis Framboise lambic stands out as light, fruity, and more like a fruity soda than a brew. 810 7th St. NW; 202-289-2030 or lovethebeer.com/rfd.html

Sou'Wester When building a cocktail list to accompany the restaurant's classic Southern food menu, sommelier Carlton McCoy couldn't overlook the old-fashioned soda. His Sou'Wester Root Beer Float ($10) punches up house-made root beer with the addition of Jack Daniels, vanilla whipped cream and bitters (click here to download the recipe). 1330 Maryland Ave SW; 202-787-6040 or mandarinoriental.com