when leasing a car do you have to put down a security deposit??

Depends on the Lessor. Sometimes they can waive the security deposit, usually when you have leased wityh lessor before. Sometimes they adjust the lease rate to substitute it. Just ask which is the better option. Do the math and see which one works out better.

i dont think so, but i do think you have to pay the first month up front

When you lease, you pay for only a portion of a vehicle's cost, which is the part that you "use up" during the time you're driving it. You have the option of not making a down payment, you pay sales tax only on your monthly payments (in most states), and you pay a financial rate, called money factor, that is similar to the interest on a loan. You may also be required to pay fees and possibly a security deposit that you don't pay when you buy. You make your first payment at the time you sign your contract — for the month ahead. At lease-end, you may either return the vehicle, or purchase it for its depreciated resale value.