Graduating to a sippy cup is an important milestone on your toddler's transition to a "big-kid" cup. However, these mess-minimizers have their share of critics, from dentists who warn about lisps, overbites and tooth decay to one parent who sued baby product-maker Playtex, claiming their sippy cup harbored mold she believes gave her child autism. Scientific studies have even linked them to chronic disease. Despite the risks, these tiny sippers can—when used correctly—be a safe, mess-free tool to help your toddler build the motor skills necessary to handle a regular cup. How do you know if you're using your sippy cup the right way—and what are the consequences if you don't?

Worrying about the critics can make you crazy, but navigating the world of sippy cups isn't as tough as it seems—you just have to look in the right place for answers. Here's a quick guide and a little expert advice to help you navigate the sippy cup minefield, and transition safely from the bottle.

  • When do I start? Ask your baby. As soon as she has the motor skills to hold a sippy cup, she's ready to take one on. Most babies will have mastered these motor skills between six and nine months. Get started soon, because you won't have the luxury for long. The American Academy of Pediatrics advises parents to stop sippy cup use between ages one and two, because dentists warn that prolonged use could lead to lispy overbites. Plus, you'll want to take advantage of your child's relatively agreeable demeanor before the "terrible twos" kick in.
  • What kind should I buy? You're overwhelmed by the aisle full of little plastic cups, and your little one's wailing from the shopping cart. Take a deep breath, relax, and begin reading labels. Sippy cups are cheap, and learning what works is all about trial and error. Clear, graduated cups are a great choice if you're keeping track of juice rations, while toddler cups with straws encourage complex jaw and mouth muscle development. Certain models are easier to clean, while others leak so little that they're hard to drink out of. Online reviews and daycare mom opinions can help you avoid duds—the rest is up to personal choice.
  • Why won't she drink!? Give her a break, change is hard! Dr. Melvin Heyman, professor of pediatrics at the University of California, suggests starting slowly. Take a sip, say "mmm," pat your tummy, and act content. Hand the sippy to her, and she'll eventually copy. If she catches on but still wants the bottle, Dr. Heyman suggests sweetening the deal. Only put water in the bottle, but save the sippy cup for formula, juice and other appealing stuff.
  • What do I give her? If you value your carpet, you'll start with water. Once she stops tossing and starts drinking, your baby (under six months old) can drink formula out of her sippy cup. Put half her meal in the cup and half in the bottle to help with the transition. After six months, she can have one-half cup of juice per day. If you're using juice as a bargaining tool, you can stretch out the juice rationing by diluting it with water. When she's one, you can add 1/2 cup whole milk to her sippy cup allotment.
  • She can just hang out with it right? Not according to experts like Ann Douglas, author of Mealtime Solutions for Your Baby, Toddler and Preschooler. She advises parents to relegate juice and formula to meal or snack time. "You don't want her to turn to food to soothe herself every time she's feeling stressed or bored." warns Douglas. Plus, the sippy cup's slow flow promotes pooling liquid in her mouth, which—like sleeping with a cup—can lead to early cavities. If she's thirsty between meals, give her water no matter how much she begs.
  • Will I give her autism? Highly unlikely. However, mold and bacteria do grow abundantly in unwashed sippy cups, so scrub the sippy cup with soapy water, or at least rinse it, after each use. The link to nueral disorders is still just a theory, but mold and bacteria will certainly make your tiny tot sick. If you smell anything foul after a wash, throw the sippy cup away.
  • A word on plastics. If you don't have enough to worry about, feel free to add bisphenol A (BPA) to your list. In 2008, the Journal of the American Medical Association published a rash of studies that linked BPA to an increased risk of obesity, early-onset puberty, heart disease, type 2 diabetes, and liver complications. The studies aren't conclusive, but they were enough for Canada to outlaw the chemical and many US manufacturers refuse to carry it. If you're worried too, look for "BPA Free" plastic or lightweight metal options before you buy.

Once you've got the facts, choosing the right sippy cup can be a painless process. There will still be spills and tantrums, but you'll learn to keep a towel handy. Stick to the rules, and you and your baby will get through this major milestone with flying colors—just in time for the next battle of wits!