I have talked extensively with the parents about this and other issues. Her mom said she's never seen her do anything like this when she is with other kids, but luckily, she did witness her do it while she was picking her up one day. In fact, she has regressed in many ways recently. She cries a lot, especially when we are out...she wants me to hold her all the time, which I can't/won't do and screams and cries if I don't. The bullying doesn't happen in reaction to another child's actions. Often the kids are sitting at the table eating and she just suddenly looks at her victim and screams (she actually gets a squinty eyed look first...it's incredible!). Or the other kids are playing nicely and she just walks over and screams, causing crying from her sensitive victim. She will say "alone"...she knows that if she does it she has to go sit alone, but that does not deter her! If I parition an area, she can still look over the gate and scream, so she's still be able to do it. I don't want to have her sitting in her booster seat in time-out all the time...that isn't good for her either, but I have to protect the other kids. I have tried putting her in a playpen and she actually enjoyed that and later asked to go in again