Other than water there are two more ingredients-- powdered milk and active culture yogurt. I use non-instant powdered milk. I've used the instant powdered milk and it works fine also, you just need to use more of it. You'll also need some yogurt as starter, shown here is Dannon All Natural Nonfat Yogurt. I've also had very good luck with Aldi's plain yogurt. As long as it says it has active cultures and is plain yogurt (not fruity and sweet) it'll work great. You only need a heaping spoonful and if you make yogurt regularly you can save a spoonful from your old batch to make a new batch.