Jay Z and Beyonce supported Serena Williams at Wimbledon, with Beyonce in a $395 Self Portrait White Ruffled Lace Military Cape Dress:

Equipped with long sleeves, a chiffon ruffle and tiny pom-poms accent the sheer lace yoke on this romantic Self Portrait shift dress.

I actually had my eye on this dress for a while, which is how I recognized it! Get it from the following retailers: