Another hitting thread I'm afraid..How do I get 2.5 year old DS to stop hitting his sister? I'm starting to go insane!

[missgrisly]

To cut a long story short, there are 11 months between DS and DD and DS will just not stop hitting DD (she is 17 months btw) - yesterday was the worst day ever. He was practically climbing over me to get a proper swipe at her.

It's not even like they are with each other all the time as my mil watches DS in the afternoons when I'm at work while my mum watches DD. As soon as he is put in the same room as her though, he will lash out.

I have tried naughty step, praising good behaviour, having toys taking away from him but it doesn't work. Has anyone else got this? I think I'll go and buy myself a referees whistle later on

Generally with unwanted behaviour I advocate the rule - If you don't want more then learn to ignore - but obviously in this case you can't let your son keep hitting his sister. However while this is upsetting for you and your daughter, its essential not to make this into a big issue because if he gets your attention (even if its negative attention with you getting angry and/or upset) he will keep on doing it. Praising good behaviour is the way to go here BUT it takes a long time and needs absolute consistency from all involved in looking after both children - and I absolutely realise all I'm suggesting is so much easier to say than actually do!!!!!
You have to say his name (saying a child's name before an instruction is an absolute must so all are clear who the meassage is aimed at) followed by telling him NO firmly but calmly when he does hits or goes to hit. If necessary stop him from hitting her by picking him up and taking him away from his siter. Then briefly ignore him while giving attention to his sister. As soon as (and the AS SOON AS is the key here) he stops the unwanted behaviour (even if he just moves himself away from his sister and looks out a window or something else so long as the something else isn't destructive or harmful), then again calmly say his name followed by simple praise e.g.thats nice, and give him your attention again.
Its important that you find the time to give him attention when he's behaving well and try to ignore all other unwanted behaviour unless its dangerous.
This is a really tough one so good luck!