State Inspections 
The Massachusetts Vehicle Check Program provides a combined safety and emissions inspection.
Each inspection begins with a visual check of the vehicle. Items such as license plate, vehicle description and VIN are compared against the registration. Once the visual inspection is complete the vehicle is then connected to states inspection machine and your emissions systems is checked for compliance. This is an annual inspection to make sure your vehicle is safe for the road, according to Massachusetts standards.
Couple of things you should know before you arrive for your inspection:
State Inspections are taken on a first come, first serve basis. If you wait till the end of the month to get a sticker, you may find yourself waiting in a lengthy line. Being aware of your vehicles condition before you go may save you some time and aggravation. For starters if your vehicle has a “check engine light” on the dashboard you should have that checked before you attempt to get a sticker as that is likely an emissions failure. To help you determine if your vehicle is ready for an inspection here is a list of the top ten most common items needed to pass for a MA State Inspection. By making sure you check these items off your list you will save you time and aggravation.
Commercial Vehicle Inspections
As defined by the Registry of Motor Vehicle Regulations for Commercial Motor Vehicle Inspections 540 CMR 4.02: Special Definitions:
A Commercial Motor Vehicle shall mean any motor vehicle which is not a private passenger motor vehicle, antique motor car, motorcycle, auto home, house trailer, taxicab, ambulance, hearse, livery vehicle, or school pupil transport vehicle. A commercial motor vehicle shall include the following vehicles:
(a) The vehicle has a gross vehicle weight rating or gross combination weight rating of 10,001 or more pounds; or
(b) The vehicle is designed to transport more than 15 passengers, including the driver: or
(c) The vehicle is used in the transportation of hazardous materials in a quantity requiring placarding in accordance with the Hazardous Materials Regulations of the United States Department of Transportation. Any commercial motor vehicle that singularly has a gross vehicle weight rating of 10,001 pounds or less and is designed to meet emissions standards, shall be submitted for an emissions inspection in addition to all applicable safety inspection requirements. Or
(d) A single, full or semi-trailer, used in commerce, with a manufacturer’s gross vehicle
weight rating over 3,000 lbs; or
(e) Any vehicle which has a vehicle weight, or curb weight, of more than six thousand pounds, as per the manufacturer’s description of said vehicle, unless such vehicle is a sport
utility vehicle or passenger van, or a pickup truck or cargo van meeting the definition of private passenger vehicle; or
(f) Any vehicle which has five or more wheels on the ground.
The Massachusetts Commercial Motor Vehicle Inspection is equivalent to the annual Federal Motor Carrier Safety Administration (FMCSA) U.S. Dept. of Transportation (DOT) Inspection. This allows motor vehicle owners to meet state and federal requirements with one inspection.