The Alabama Department of Public Safety (DPS) does not mention any passenger restrictions for those ages 15 or older with a learner's permit. So it is our understanding an AL permit holder can carry other passengers with him or her in the vehicle along with their supervising driver of course. You can verify this with the DPS since state laws, especially those surrounding teen driving laws, are changed and updated often it seems.
According to the Alabama Department of Public Safety and the AL driver's manual any person in this state 15 years of age may obtain a restricted Learner’s License for the purpose of learning to safely and effectively operate a motor vehicle. Upon passing the required examination, the applicant will be issued a Class D Alabama driver license with a “Y” restriction.
The “Y” restriction indicates that the holder may operate a motor vehicle while accompanied by a person who is 21 years of age or older and, who is duly licensed in this state or a licensed or certified driving instructor occupying the seat beside the operator. After the holder’s sixteenth birthday, the holder may operate a motor vehicle with any licensed driver occupying the seat beside the driver.
If you are under 18, you must hold your learners permit for at least 6 months and you must practice driving with your parent or legal guardian for at least 30 hours. The teen driver can then move up and apply for a restricted driver's license. Upon passing the required road test, the driver will be issued a new regular license with the “Y” restriction removed. Now as a newly licensed or restricted licensed driver there are conditions on the amount of passengers you can carry.
A newly licensed Alabama driver that is under the age of 18 is under some restrictions and conditions. One such conditions it that he or she may not have more than 4 occupants in the vehicle, excluding a parent or legal guardian of licensee. So 3 passengers and the driver or 3 passengers, the driver and a parent would be the maximum limit one could have in the car according to the passenger restriction.
You can read about this restriction under Alabama code Section 32-6-7.2. Here it also notes that violations by newly licensed AL drivers under the age of 18 shall not result in a suspension of the person's driver's license, but shall extend the time period for six months that the person is subject to the restrictions before the person is eligible to be designated as an unrestricted driver's license holder or until age 18.
Most states have laws along these lines, that there are not passenger restrictions for permit drivers, since they must have a supervising driver in the front seat with them at all times however once they move up to the next stage of the graduated driver's license (GDL) program where they can drive without supervision there are passenger restrictions put in place by the state. This is due to the studies showing an increase in accidents and fatalities caused by distractions from having other passengers in your vehicle.