Ice cream is a desert enjoyed by many people, but it is quite vexing when it melts. It is, after all, a frozen food, so any temperature over 32 degrees is going to make it turn into soup. The key to keeping it from melting is to prevent the ice cream from crossing the 32-degree threshold -- you need to find a way to keep it cool, and you need to do so quickly, as the hotter the outside temperature the quicker it will melt.
Go straight home from the grocery store. Cars get hot, so if you run other errands and leave the ice cream in the car while you do so it will probably melt.
Put the ice cream away before any other groceries when you get home.
Keep your ice cream in the freezer, not the refrigerator.