Tameshiwari literally means "test cutting"– and it's one of the premier events of The Pacific Tournament. In a tameshiwari event, competitors strive to successfully complete the most difficult and technically demanding "breaks" of various materials. The most common type of tameshiwari is breaking "boards" – one-inch thick pine boards, stacked one on top of another, and oftentimes separated by small sticks called "spacers" in-between each board.

However, pine boards aren't the only types of materials used in this event: roof tiles, cinder blocks (usually so-called "half-blocks") – even baseball bats can be used.

Adult tameshiwari events are divided into a Men's and Women's division, and Teens (14+) are also divided into two gender-specific groups. Some tournaments also have weight divisions in Tameshiwari, but The Pacific Tournament does not.

All materials used by competitors during their breaks must be approved by the tournament judges – this ensures that all materials are comparable to each other, and haven't been doctored in any way.