am i here legally?

If you're not gonna stay for more than 90 days in a row you probably won't need any permit but since you said you're working it might be different. I think it's better if you check with your embassy. Anyway no worries, in case you need to straighten your position you'll have plenty of time to do it before they put you in jail

If you have no other visa, that means you're technically a tourist in the eyes of immigration, so the rule you are probably under now is the Schengen rule. This restricts an American to 90 days of any 180 day period in any Schengen country.

so, if you spend 90 days in Italy and then go to France, you're technically overstaying the tourist allowance and could get into trouble when you try to leave the Schengen zone. As with the previous poster, I recommend talking to your embassy to sort this out.

Katy, if you are earning money then it is surely illegal in the eyes of the Italian govt.  You must receive a code fiscale in order to work in Italy (the government wants to collect their taxes on your income). 

If it is purely an educational experience, I think there is a separate, easier to obtain visa.  Since you are already here it may be easier and faster than typical.  Check the following website to see what you need.

http://www.esteri.it/visti/index_eng.asp

I would also speak with your internship host on this matter. Good luck.