As a landlord, what deposits can I request of a tenant at or prior to the commencement of a tenancy?

At or prior to the commencement of a tenancy in Massachusetts, a landlord may only accept the following monies from a tenant:

• First Month's Rent
• Last Month's Rent
• Security Deposit (not to exceed one month's rent), and
• Key Charge (equal to purchase & installation costs for a key and lock)

Any additional monies accepted can result in a landlord being held liable under Massachusetts law and subject said landlord to treble damages and attorney's fees.