In preparation for a garden party reception at my house, I went to see my tailor.  The dress code of the party was the ever elusive "resort-formal" (sometimes referred to as "formal resort") and I decided to have a suit made for the occasion.  As I reached my tailor’s workshop in Empire State Building I was stopped by the police.  Somebody was on the ledge, about to jump.



Police were scrambled everywhere and poised to arrest the man on the ledge. Not to be brash, but suicide is a very strange crime to arrest someone for.  You are only guilty of it if you attempt but don’t commit.  The "jumper" turned out to be a tastelessly placed statue, so life went on as usual and my ancient tailor only stuck me about five times with the needle.
The rest of the day I spent fielding calls from friends of mine about the dress code and whether "resort-formal’ was a condition of entry, or just a suggestion.    I found myself delicately re-explaining to my invited guests, "The dress code is for your comfort and the comfort of others so that no one feels over or under dressed."  When a party invitation does you the favor of not wondering what other people at the party might be wearing it’s like suicide: it’s only a crime if you don’t commit.
Resort formal is simply the best and most comfortable dress code for warm weather receptions of all kinds.  Put it this way: if you could accept an award at the Cannes Film Festival in a dress and already be wearing your bathing suit for the afterparty, you are probably in perfect resort-formal attire.
For ladies this means a simple floral-inspired wrap dress and any pair of flat sandals.  This is probably the one time in your social life where a little black dress won’t do.  Unless, of course, I have died and you are throwing me a resort-formal funeral.  If so, you might fight yourself trotting around, dancing in the grass, and you don’t want to sink your heels into the dirt.
Resort formal never ages.  These dresses from last summer’s Douglas Hannant resort collection can be worn on the anniversary of whatever party you wore it to last year.  The key is to select simple garments that are effortless to wear. There are no control-top panty hose or strapless bras in resort.  If your dress has a zipper, it should be somewhere accessible on the flank so you can pull it off and take a dip in the pool.  Let your bikini ties hang out the back, and wait for your casual attitude to follow.
Here, Jackie O takes a dress that any respectable person might wear to a job interview, and she makes it formal with pearls and gloves.  Resort formal should be as effortless as a swim, and as stately as a swan.
Resort formal gets tricky in the men’s department.  Not to be anymore sexist than I have to be, but the questions I fielded yesterday from friends came mostly from the men.  The women on the list seemed to all have splurged on a floral-inspired formal dress last season, and were still waiting for an occasion to wear it.  (You’re welcome).
The queries from the invited men seemed to be a question of mindset.  Many wondered point-blank if the dress code meant something you would wear at a resort, such as a polo shirt with a blazer.  No. You cannot. You’re thinking of Cape Cod and, in general, one shouldn’t take fashion advice from people in Boston.  
Imagine you are spending the week as a guest in the Hamptons. You wear one outfit for golf, one outfit for tennis, one for drinks at the club, and then at the end of the week you will all meet up for a sit-down dinner on the patio or under a tent.  The light-colored suit you wear to that dinner is going to be formal-resort, as seen in Mad Men Season 3.
The word formal is in the title for a reason.  This gentleman below, for example, is almost there.  He has the perfect accessory for a formal resort party (that is, he is standing next to a pretty woman in a single-piece wrap dress).  He has on a tuxedo jacket with regular black pants, and a tuxedo shirt.  He wears shoes that will be as comfortable dancing on the parquet floor as they are aboard the boat. 
If he could borrow a pocket square or a scarf to tie into something, he might not have come all the way to the Hamptons only to be turned away at the door. Below is a handy guide that any boyscout could use to roll a scarf into a stunning neck tie:
See you at the party.  Bring a chilled bottle of Sancerre rose.  You’ll be everyone’s next dancing partner.  Or if you really feel the need to bring something, follow the immortal words of George Plimton, and "Bring a pretty girl."