Will she have fun? If she doesn't want to join a team, don't make her -- it's not worth forcing her.
Does she have good hand-eye coordination? "Once your child can catch a ball with two hands in front of her with ease, she's probably physically ready to start participating in organized sports," says Sally White, Ph.D., psychology professor at the College of Notre Dame in Baltimore. If she's having trouble with basic ball skills, though, she might need some practice before she's ready for the big (or little) leagues.
Can she stick to an activity for at least an hour? That's about how long a typical game lasts. If she gets bored before then, she may ask you to take her home early, leaving her team in the lurch.
Will she follow the rules? Before your child scores a goal or hits a home run, she'll need to learn basic game guidelines. Otherwise, she could get hurt (or annoy her teammates).
Is she excited about meeting her teammates? She'll have to adapt to and cooperate with new people, and possibly deal with difficult personalities.
Will she -- and you -- be able to keep her schedule? Your child will likely have to attend at least one practice and one game each week. Keep that in mind before you make a commitment you both regret down the road.