My son is 21 months; I like to say he's a member of the clean-tray club. When he's done eating, he cleans his tray by sweeping all the leftover food to the floor. :) So I feel your pain. First, any food he dumps, I wouldn't give him back. No matter how much you want to try to recycle it - DON'T give it to him. This isn't for sanitary reasons (though they're important) so much as it is because you need to teach him that food he throws doesn't return. Second, be consistent in the discipline. The one I've found really works is time-outs. If you want throwing food to get an immediate time out, then do it. My son's time-out is in his pack-in-play in another room. I tell him why he's going there and that he'll stay for one minute. (The general rule is 1 minute in time out per years of age.) He screams bloody murder for the minute (or so, I don't really watch the clock, I'll admit) and then I go get him, reminding him that I love him but that he can't do whatever. Usually this curbs the behavior - USUALLY. Sometimes there's several time-outs in a row, and on one noteable day, we had 7 (all for different reasons!). But mostly, he's stopped doing the things that put him there, within a week of starting the process. Third: be FIRM. Don't give in. And maybe, while he's doing this, don't eat in public places. (Sucks, I know. I hate it too - but I hate being THAT MOM more.) Good luck.