We did both. I did the breastfeeding as often as I could and supplemented with formula, but I returned to work 4 weeks post partum for financial reasons and it was hard to get the time to pump as much as I wanted. It's actually not so common to breastfeed in my family but it was really important to me so I kept up with it for 6 months. More often than not, people were embarrassed to be around me while I was feeding her eventhough she and I were covered with a blanket. I felt really ostracized by most of my family (not my hubby, mom or one of my aunts, but the rest of them). After the 6 months, we were supplementing with baby cereal so she was getting full easier and didn't need so much from me. The second one will be the same. I'm not afraid to supplement with formula from day one, but it is important to ME to do the breastfeeding as well for all that good stuff in the milk. I know some women can't do it whether it be the baby's reaction or pain or lack of production, I wouldn't be totally devastated to just use formula. Do what works for you and your baby and don't be ashamed of it.