How To Control Aggressive Behaviour In A Child?

My 5 year old throws tantrums when he doesn t get his way, screaming and saying horrible things. Very stubborn and has just started school, he struggles with the social aspect a bit. It takes him time to warm up to people and only likes to play what he wants. Does silly things for attention that other kids don t always appreciate. My wife thinks he has a problem and may possibly be on the scale, I don t agree and think it s normal behaviour and want to be stricter but she argues that he can t help it.