Everyone's financial picture is different, so it's impossible to answer this one across the board. Families with a lot of debt, like school loans, car payments or credit card bills, will probably have a tougher time adjusting to one income than a family with only a mortgage and incidentals. First, take a long, hard look at your current expenses and be sure to consider the impending costs of childcare and other baby expenses to see how things will change. Then, spend several months before you quit your job living on the budget you intend to adopt. You'll have to make some lifestyle adjustments, but tightening the old belt will give you a clearer picture of what life will be like on one salary; plus you'll save some much-needed moolah in the process. Many financial advisers advocate the "cash only" system because it's harder to part with cash than it is to swipe a credit card, and it makes you more aware of how much you're spending.