State Representative McCarthy represents the towns of Abington, East Bridgewater, and Whitman in the Massachusetts House of Representatives.

At an early age, Allen learned the importance of public service from his father, former Massachusetts state representative and senator, Robert McCarthy. A graduate of East Bridgewater High School, Boston College, and Boston College Law School, Allen served as an assistant district attorney and civil litigation attorney for many years before his election in November of 2006.

Currently in his second term in the legislature, Allen has advocated for increased local aid, promoted state investment in the local economy, and sought greater resources for substance abuse services. As Vice Chairman of the Joint Committee on Education, he works closely with Chairwoman Marty Walz on the direction of K-12 education policy in Massachusetts. Allen also serves on the Joint Committee on Financial Services, which oversees the state’s banking and insurance industries, and the Public Service committee, which reviews policies governing state employees.  In early 2009, he was a member of the House Special Committee on Pensions. The panel’s recommendations become the basis for landmark pension reform legislation that passed later in the spring.

Prior to his time in the legislature, McCarthy served as a prosecutor in Middlesex County. Starting in Lowell District Court, his work was recognized with promotions to district court supervisor and assistant district attorney in the Middlesex Superior Court. He is a recipient of the Scott Harshbarger Award for Distinguished Service to the District Courts of Middlesex County.

After leaving the District Attorney's Office, McCarthy worked for several years as a litigation attorney in Boston while also serving as counsel to the School Transportation Association of Massachusetts.  He now maintains his own law practice in West Bridgewater. Allen often credits his experience as a prosecutor and trial attorney with giving him the opportunity to fight for some of the state’s most underserved individuals.

A native of East Bridgewater, McCarthy currently lives there with his wife Diane, a first grade teacher at the East Bridgewater Central School. They have three children, Abigail, Stephanie, and Coleman.