Long sidelined as the least lovable part of a three-piece suit, the vest is emerging as a solo star—on the runway at John Varvatos, in the windows at J. Crew, and on the backs of Justin Timberlake and Adam Brody. Be thankful that style arbiters have put their stamp of approval on something truly wearable (unlike, say, formal shorts), and memorize the following guidelines before you co-opt it:

It’s a vest, not a tank top. You can layer it over a short-sleeved tee or a printed shirt (if your aim is to look casual) or a starched button-down shirt and a tie (if your goal is polish).

Baggy, unbuttoned vests were abolished in the late eighties. Rather than channel Corey Haim, make sure yours is snug but doesn’t fit so tight that you can’t button it.

The vest makes a statement on its own—it doesn’t need loud prints. Stick with something low-key like a gray, black, or dark plaid wool version.