Hi there,
To make a long story short... I am in Massachusetts. I have a condo for rent. Found a tenant. She wanted to move in ASAP, I tried to accommodate her so I rushed into signing the lease and getting it to her (through a third party). Right as the third party handed her the lease (I was not present) I realized I didn't have keys to give her and so I called her and told her that she would have to wait as I didn't have the keys. She took the lease (already signed by me- STUPID, I know) and left. She never left any money, never got keys... Is her lease valid (assuming that she did in fact sign it)? Or did she need to pay me to bind the lease?
Thanks guys!

Signatures by both the landlord and tenant are what make the lease binding. If you still haven't received a signed lease from her, send her a letter by either certified mail or hand delivery, telling her that she has 3 days to deliver a fully-signed lease to you. Then say that if she doesn't return the fully-signed lease in that time then you will consider the lease null and void and you will lease the condo to someone else.

Thanks so much Lisa. That is what I figured the answer would be, but was hoping money changing hands would be necessary to seal the deal, since this woman has turned out to be a nut. I'll try your advice though. Thanks :)