Changing pad. Most bags come with a rectangular changing pad that folds up and fits in the bag and can be wiped clean. Many pads fold to fit into a designated pocket. Some have a semirigid interior that helps maintain the pad's shape. But some are cushier than others. Cushy is better.

Construction. Look for wide, padded, adjustable shoulder straps, well-reinforced seams (tug on them to make sure they're strong) and quality hardware--heavy-duty plastic or metal zippers and sturdy closures. Zippers, rather than magnetic closures, ensure that your stuff won't fall out if your diaper bag tips over.

Handles vs. hands-free. The handles of a tote-style bag should be short enough so that the bag doesn't drag on the ground when you carry it like a suitcase, but long enough so it can be slung over your shoulder or worn on the diagonal. Wide or well-padded straps are more comfortable. A backpack, messenger, or sling-style diaper bag keeps your hands and arms free. A backpack's shoulder straps should be adjustable for proper fit, and a sternum strap, which connects the shoulder straps at the upper chest, helps redistribute the weight to make lugging baby gear more comfortable.

Fabric. Bags made of quilted fabric or silk are often favored by gift givers, but heavy-duty, moisture-resistant nylon or microfiber is more practical, especially if you're planning to have more than one child and you want the bag to go the distance. Beware of vinyl bags if you live in a cold climate. They can crack when the temperature dips. And you'll want a diaper bag that's washable inside and out.

Color. Some manufacturers continue to offer "baby colors"--pastels and light-colored prints. But dark shades are less likely to show stains.

And if you go for a more adult look, you can consider using the bag for other purposes when diapering days are over, assuming it has held up well enough. Still, make sure the interior is a light color. Otherwise, you will find yourself digging for items in a black hole.

Storage. Easy-to-access, zippered interior and exterior compartments, which can function as a wallet and as storage for things you constantly need such as baby wipes, pacifiers, and your cell phone, are a convenient plus. Make sure the zippers are heavy-duty so they'll hold up. Clear vinyl or mesh pockets inside can hold diapers, wipes, and other baby gear. If you'll be taking lots of outings or doing lots of traveling with your baby, look for a bag with an insulated cooler section. Bottle pockets are handy, but make sure they fit your brand of baby bottles or your favorite bottled water or juice for older babies. Always keep bottles and food away from dirty diapers.