Under Massachusetts General Laws Chapter 151, Section 1A, if an employee works more than 40 hours in any given week, he or she must be paid "one and half times the regular rate at which he is employed" for any time in excess of 40 hours.  However, you did not specify what your job is, and Section 1A provides the following lengthy list of exempt employees:
 
This section shall not be applicable to any employee who is employed:
(1) as a janitor or caretaker of residential property, who when furnished with living quarters is paid a wage of not less than thirty dollars per week.
(2) as a golf caddy, newsboy or child actor or performer.
(3) as a bona fide executive, or administrative or professional person or qualified trainee for such position earning more than eighty dollars per week.
(4) as an outside salesman or outside buyer.
(5) as a learner, apprentice or handicapped person under a special license as provided in section nine.
(6) as a fisherman or as a person employed in the catching or taking of any kind of fish, shellfish or other aquatic forms of animal and vegetable life.
(7) as a switchboard operator in a public telephone exchange.
(8) as a driver or helper on a truck with respect to whom the Interstate Commerce Commission has power to establish qualifications and maximum hours of service pursuant to the provisions of section two hundred and four of the motor carrier act of nineteen hundred and thirty-five, or as employee of an employer subject to the provisions of Part 1 of the Interstate Commerce Act or subject to title II of the Railway Labor Act.
(9) in a business or specified operation of a business which is carried on during a period or accumulated periods not in excess of one hundred and twenty days in any year, and determined by the commissioner to be seasonal in nature.
(10) as a seaman.
(11) by an employer licensed and regulated pursuant to chapter one hundred and fifty-nine A.
(12) in a hotel, motel, motor court or like establishment.
(13) in a gasoline station.
(14) in a restaurant.
(15) as a garageman, which term shall not include a parking lot attendant.
(16) in a hospital, sanitorium, convalescent or nursing home, infirmary, rest home or charitable home for the aged.
(17) in a non-profit school or college.
(18) in a summer camp operated by a non-profit charitable corporation.
(19) as a laborer engaged in agriculture and farming on a farm.
(20) in an amusement park containing a permanent aggregation of amusement devices, games, shows, and other attractions operated during a period or accumulated periods not in excess of one hundred and fifty days in any one year."
 
If, based on the above information, you believe you are not being paid in accordance with the law, I would try talking to your boss about it.  If that does not work, try contacting the Attorney General's office ((617) 727-2200).  Massachusetts General Laws Chapter 149, Section 150 provides for triple damages for wage law violations.  Good luck.