I received a party invitation that read: "Please bring a dish to share - a bottle of wine or soft drink will be acceptable from male guests. :-)" Because this was sent to students mostly from other countries, the host may have felt the need to spell out what many Americans already acknowledge. Women are expected to cook or, at the least, buy a side dish or dessert for a potluck. Men get less criticism for bringing less.
If men, especially younger heterosexuals who drink alcohol, are running the show, you can count on plenty of alcohol, but you should have dinner beforehand. If women are in charge, it's a good bet that there will be food.
What do you bring to the party?