A Practice Note discussing "other transaction" (OT) authority of certain federal government agencies, particularly the Department of Defense (DOD), to enter into other transaction agreements (OTAs) with contractors for research and development. This Note reviews OT authority, which agencies and contractors are eligible to enter into OTAs, and explains the differences between OTAs, procurement contracts, cooperative agreements, and grants. This Note also addresses key considerations for contractors when negotiating an OTA with the government and how contractors can challenge the solicitation or award of an OTA.