May through August is known as trauma season, a period when children sustain almost half of all yearly injuries, according to Chrissy Cianflone, home safety program manager at Safe Kids Worldwide. In the summer, kids are outside more and are extra physical and less supervised, so parents need to be more aware and watch kids attentively—not in between reading a magazine or talking on their cell.

Here are the most frequent child accidents and simple steps you can take to avoid them so that your summer is as it should be—fun and worry-free.

Top Safety Tips

Drowning The risk factor for drowning goes up 89 percent for all kids in the summer and is the season's leading cause of death among children ages 1 to 4. Drowning can happen suddenly and silently, says Cianflone. Always have a designated adult just to watch kids near a pool or hot tub, and install high fencing with self-latching gates around these areas.

Bicycle, scooter and other wheeled-toy-related accidents More than 251,000 children ages 14 and under were treated in ERs in 2005 for bike-related injuries, and close to 150,000 kids were treated for inline-skating, roller-skating, nonmotor-scooter and skate-boarding injuries in 2004. Make sure your child always wears a helmet. (For tips on wearing one properly, go to www.usa.safekids.org.) And teach her the rules of the road.

Falls Summer calls for open windows, but be aware that falls are the leading cause of accidental injury among children, especially those 10 and under. Install guards on all windows above the first floor (screens are not sufficient). Never allow kids to play on a balcony, roof or near unprotected windows.

Pedestrian accidents Children cannot reliably judge speed, spatial relations and distance until they're at least 10. So younger kids should never cross the street without an adult.

Motor vehicle accidents Many families are on the road in summer. Follow car seat safety guidelines for children under 14 from the APA. Teach children to never play around parked cars, and if you're the driver, be sure you "spot the tot" before starting the engine—walk all the way around the car to make sure no child is in harm's way.

Updated with new 2011 car seat guidelines

Editors note: Motor accidents are the number one killer of children in the US.