Maybe it's not your fault -- the one strawberry rhubarb pie on the dessert table was the only one of its kind, to be shared among dozens, but you didn't know that when you went back for a second slice. Nor your third.
While you'll have to rely on guests to control their love of seconds and thirds, if you're the party planner, take advice from the most seasoned party throwers out there. Estimate how much pie -- and food and beverages -- you'll need for each of your guests as soon as you have a solid guest list to avoid running out of food. In general, plan that every adult will eat about a pound of food (and about half that amount per kid), including everything from appetizers to the main course to condiments and dinner rolls.
If you're serving alcohol at the reunion, you'll want to plan on each adult drinking two drinks in the first hour and one drink every additional hour they stay at the party. Figure on pouring one bottle of wine among eight people, and if mixed drinks are on the menu, figure one gallon will serve 10 guests one drink each.