We have a 6 month old English Bulldog, Reggie. We have a 9 year old son and 3 year old daughter, too. At first he would "attack" the kids if we weren't right there to stop him. We have done training and have worked on some dominance techniques. These have all helped. However, when our kids start playing, running, jumping, etc., Reggie thinks it's playtime and he joins in. He jumps on them, chases them, and does all kinds of things. He thinks he's playing. We've had to work with our kids to make sure that they don't start "playing" in the house when Reggie's around because he doesn't yet understand what's going on. That has helped a lot. We really try to keep him in a different room or outside if the kids are "playing" in the living room.