No hitting

Why do kids hit other kids?  There's not always an easy answer to that question.  They might be tired, or frustrated, or imitating someone they saw hitting, or angry or any of a number of reasons.  But regardless of WHY they hit, your responsibility as a mother is to see that they DON'T hit another person, child or adult.  That is an unacceptable behavior.

The most important thing you can do is not be an example of someone who hits.  If you don't want your child to hit, then don't hit either.  Ever.  If you do, then you need to work on your own behavior first.

Then, in as calm and firm a voice as possible, tell your child, "No.  No hitting."  "We do not hit."  Be simple and straightforward.  A toddler can understand what you are saying.  Repeat every time your child hits someone.  No yelling, screaming, or long diatribes on the evils of hitting.  The important thing for your child to hear is that what he is doing won't be tolerated.

If he still cannot control himself, it's time to remove him from the situation.  Put him in time-out or in his room or take him home.  Show that you are serious.   Be consistent.

As with most undesirable behaviors, you're going to have to do this over and over again until he finally gets the message that there are predictable consequences to his behavior.  It would be nice if you only had to tell a child once to stop doing something but be realistic.  It isn't going to magically happen the first time...or the second.   If it's any consolation, the sooner you get involved, the sooner his behavior will stop.