A South Dakota roommate agreement is a written document detailing the rights and responsibilities of all roommates sharing a residential rental unit. The terms and conditions negotiated and entered into the agreement needn’t necessarily involve the landlord, as most of the the parties to the roommate agreement will already be in a lease agreement with the landlord. However, the provisions in a roommate agreement cannot compete or interfere with those in the original lease document. Provisions included in a roommate agreement are rent payments, utilities, chores and other household duties, allowance of pets and guests, smoking rules, and noise limitations.