Clothes that you are comfortable moving in. You will be getting up and down off the floor and moving quickly. Make sure they are clothes you are ok sweating in. You will sweat. In the nicer months we will work out outside if the weather permits it. There are tons of CrossFit-specific clothes and shoes out there but you do not need any of that for Foundations. If you are looking to upgrade the wardrobe we can point you in the right direction.