12U lacrosse is where we see the final changes in the game, games are now played on a full size field and the game moves from 7 on 7 to 10 on 10. With this change teams use 3 players at attack, defense and midfielder. In addition to the increase in players penalties are now called and enforced as releasable or non-releasable if the opponent scores on a man advantage. The same rules apply as in 10U in regards to possession and the ability for defenders to take the ball up.
A few technical details that start to get introduced is the use of a LSM which is a Long Stick Midfielder, the responsibility of this player is to have an additional defender in the event your team loses the face-off, if your team wins the face-off these players rush off the field to get an attack stick midfielder on. In addition to this you have shifting on defense to make use of the additional defender on the field. With the additional room on the field as well you will see the use of slowing the game down to wait for players to get set up and more control moving the ball behind the net to what is called the X man.