D.M.
Hi Jessica
My little boy didn't scream, but his best little girlfriend did and I thought her mother handled it beautifully - and it worked.
When she screamed her mother would calmly simply say, 'No, we don't scream in this house.' and walk away so she didn't really get any additional attnetion for the screaming and any attention she was getting - like if her daughter screamed while they were playing - immediatley ended.
She would come back a few minutes later and say, 'Are you finished screaming?' and if she stopped screaming she would stay and continue whatever they were doing, but if she screamed again she would repeat the 'No...' and leave scenario.
It took about a week, but she is no longer a screamer and trust me we're all happier for it.
Hope this helps. D..x