The Federal Motor Carrier Safety Administration (FMCSA) is the agency of the U.S. Department of Transportation that is responsible for establishing standards for Commercial Motor Vehicle (CMV) operators, including the Commercial Driver's License (CDL). The minimum national CDL testing standards and licensing requirements established by FMCSA are administered by state driver licensing agencies when they issue a CDL. You are required to obtain and hold a CDL if you drive interstate, intrastate (within a state), or for foreign commerce and drive a vehicle that meets any of the classifications of a CDL. States develop their own tests which must meet the minimum federal standards, but which also may have standards unique to the state. To get a CDL, first you must get a commercial learner's permit. States can only issue learner's permits and CDLs to drivers after they pass knowledge exams and skills tests. You have to pass the CDL knowledge and skills tests for the class of license and type of endorsement required to operate the type of commercial vehicle you plan to drive. And, you have to take the skills test in a vehicle of the same type as the vehicle you plan to operate. For a quick reference of CDL Classes, see the CDL License Matrix.
