Bus drivers must have a commercial driver license if they drive a vehicle designed for 15 or more people, including the driver. Bus drivers must obtain a passenger endorsement on their CDL. The material for this specific endorsement is covered in Section 4 of the CDL manual. This study guide covers the material on Section 4 for the Passenger Endorsement, including the main topics you need to know and a variety of professionally designed practice questions for review.
Note that if your bus has air brakes, then the air brake endorsement is also required. The air brakes endorsement is a separate and different endorsement.