The United States Soccer Federation (USSF) recently approved new player development and safety initiatives. As a member of USSF we will follow their guidelines. 

There are two distinct initiatives: 

1.   Player Safety : goes into effect immediately 

2.   Player Development : goes into effect fall of 2016

A lot of focus has been on the change to birth year and field sizes but you need to also be aware of the player safety change regarding heading in the younger age groups.

Starting this spring (now)

U11 and younger player cannot head the ball.

U12 - U13 has limited heading.

Here is the USSF rule:

HEADING 

1. U11 and younger. a. U.S. Soccer recommends that players in U11 programs and younger shall not engage in heading, either in practices or in games. 

2. U12 and U13. a. U.S. Soccer further recommends for players in U12 and U13 programs, that heading training be limited to a maximum of 30 minutes per week with no more that 15-20 headers per player, per week. 

3. All coaches should be instructed to teach and emphasize the importance of proper techniques for heading the ball.

To clarify: U12 and U13 can head the ball during the game but are limited in practice.

Referees have been instructed to handle heading in the following manner:

"[A]n indirect free kick (IFK) should be awarded to the opposing team from the spot of the offense. If the deliberate header occurs within the goal area, the indirect free kick should be taken on the goal area line parallel to the goal line at the point nearest to where the infringement occurred. If a player does not deliberately head the ball, then play should continue."