It’s a lovely way for family and friends on both sides to start getting to know one another. There’s little formal rules and that means you have plenty of latitude. Cocktails and hors d’oeuvres at a parent’s home, dinner in a restaurant, a Sunday brunch or an outdoor barbecue would all do it.
There are no rules about when to hold the party but it usually takes place at least two months after the engagement and no later than six months before the wedding. A lot depends on the length of the engagement. If the engagement is six month or less, there usually isn’t time for a party.
There is no formal tradition governing engagement gifts, other than between the couple. Since you’re not supposed to expect gifts at the party, you don’t need to register before the event. From a practical standpoint, you don’t want to register in a rush or before you’ve had time to decide on what you like.
The guest list should be limited to people who will be invited to the wedding, though there can be exceptions to this rule. If you’re not sure about the size of the wedding, play it safe and invite only family members and your closest friends.
The goal of your engagement party is to get the two sides mixing and mingling. The better people get to know one another, the easier all of your other pre wedding events will be.
If you want something more low-key, you could also opt for a small dinner at a restaurant. Forget the activities but go around the table and have all the guests introduce themselves, or say a little something about each person yourselves. It’s a nice way to break the ice and create a sense of ceremony.