I absolutely agree with all of the advice given so far on appropriate steps within formal processes. My next line of advice may not be extremely popular, but I completely believe it. Your child must be taught to stand up for themselves & to be forceful about it. We have taught our 8yr old son to stand up for himself verbally since he began school at age 5 and we first dealt with bullies. Let's all face the facts - we all deal with bullies and it'll never go away. Bullies will only pick on the weakest of children and/or those they are most jealous of. We have taught Clayton that often the bullies are sad individuals, so he should understand the sadness behind it, but also not put up with it. Absolutely follow processes such as speaking to the Teachers, parents, Administration, etc. But at the same time, your child should be equipped with your encouragement. He/She should be taught to stand tall, look a bully straight in the eye and say something like "I'm don't like when you ________ to me, and I'm not going to take it anymore" - saying it forcefully. 9 times out of 10, when a bully is confronted with a strong resistence, they will stop, or unfortunately, move on to another victim.
About a year ago, there was an incident at the park 4 houses down from us. I was mowing the grass, Clayton went down to play basketball with a few of his friends. A bully picked & picked on him - he put the steps in place. He ignored it...then told him that was enough and he wasn't going to take it anymore. Then when the Bully became confrontational, Clayton said he was going home. As he walked away, the Bully made fun of him & pushed him down. Clayton stood up, walked right up to him and said "I told you I had enough - stop being a Bully, no one likes that." When the boy pushed him again, Clayton grabbed him by the front of the shirt and said "It's time for you to go home now, none of us are going to play with you anymore unless you stop being so mean." The other boys stood up to after Clayton made the 1st bold move. They chimed in "Yeah - go home, we're not playing with you!" Clayton said the little boy ran home crying. We walked down to his house later and spoke to his parents and the child. Clayton apologized for grabbing him, but said that he felt like he had to stick up for himself and the other children. The boy's parents told Clayton they understood, and then asked the boy to apologize as well. They have played together fine ever since. Not without issue of course, but the boy knows that when he starts being aggressive, the other children pull away.
I guess I just feel that sometimes, the best defense is a strong offense. In no way, shape or form do I EVER condone my son getting physical. BUT - I will continue to support him sticking up for himself when pushed into a corner & will equip him with the tools and skills necessary to be defensive.