Little League International placed a moratorium on most composite bats for all of its divisions in 2011, and it remains in effect. For the Little League Division (Majors) and below, some composite-barrel bats that have proven in testing to meet performance standards through the ABI process and have received waivers (here is a current list of 2-1/4 inch composite bats that have been granted waivers and are legal for use).
For Junior League, bats may not exceed 2 5/8 inches in diameter, and composite-barrel bats must be -3 and must meet BBCOR standards and be so labeled. Bats that do not have composite materials in the barrel and meet other applicable standards can have any length/ weight ratio.
For Senior League, bats may not exceed 2 5/8 inches in diameter, and all non-wood bats must be -3 and must meet BBCOR standards and be so labeled.
The moratorium does NOT apply to composite bats in Little League Softball at the present time, but this may change in the future.
For an overview and history of the moratorium on baseball bats in Little League, click here.