Attorney Cosgrove is a 1963 graduate of LeMoyne College in Syracuse, New York and a graduate of Suffolk University Law School in 1967.

Attorney Cosgrove has extensive criminal and civil litigation experience in the Massachusetts District, Superior, Probate and Appellate Courts. He has tried cases in several other jurisdictions and is admitted to practice before the United States Supreme Court. Besides his admission to these courts, he is also admitted to practice and has extensive experience in the United States District Court for Massachusetts and the First Circuit for the United States Court of Appeals.

Attorney Cosgrove has been selected as a fellow of the American College of Trial Lawyers, an organization limited to the top one percent of trial attorneys in the United States.  He has served as State Chairman for that organization.  He is a Foundation Life Fellow of the Massachusetts Bar Foundation, a member of the Massachusetts Bar Association, the Norfolk County Bar Association, and the Quincy Bar Association.  He is a past president of the Quincy Bar Association..