Tee-ball (also teeball, tee ball or T-ball) is a team sport based on a simplified form of baseball or softball. It is intended as an introduction for children to develop bat-and-ball game skills and have fun.

Tee-ball associations generally allow children between the ages of four and seven to play in their leagues. A tee-ball coach sets the team lineup and fielding positions in the team's scorebook. The positions that get the most action in tee-ball are pitcher and first base, followed by the rest of the infield positions. In some leagues, catcher is also a special position due to the added gear that is worn; in other leagues, there is no catcher. In tee-ball, the pitcher is usually used for defensive purposes only, though gently pitched balls may be used with older or more advanced players in place of the fixed tee. The ball is placed on an adjustable tee atop the home plate at a suitable height for the batter to strike. (In some clubs, adult coaches give the batter an opportunity to try and hit a few pitched balls before going to the tee in the hope that this will further develop batting skills.) Most of the other rules are similar or identical to those of baseball, though the game is played on a smaller field, typically one used for Little League or other youth baseball. In addition, for the youngest tee-ball players, runs and outs are often not recorded, and every player gets to bat each inning.

Many parents assist during the game by coaching players in the dugout, in the field, on the bases, and at the plate. They often also perform the task of umpiring.

Bats: 25 to 26 inches long, 2.25 inches diameter, maximum weight 17 to 20 oz.

Balls: typically appear identical to baseballs, but slightly softer to reduce injuries: 9 to 9.5 inches around, 4 to 5 oz weight, with a molded core or sponge rubber center.

Footwear: Athletic footwear such as running shoes.

Gloves: 12 inches long maximum.

Safety helmets: Mandatory at all times.