Major Mastromauro is a graduate of Boston University. He was commissioned in 2008 through the Officer Candidate Course.
After completing The Basic School and Field Artillery Officer Basic Course, Major Mastromauro reported to 3d Battalion, 10th Marines. He served as a Company Fire Support Officer with Co F, 2d Battalion, 2d Marines, and Executive Officer with Battery L, BLT 2/2. He deployed in support of Operation ENDURING FREEDOM and the 22d Marine Expeditionary Unit.
Upon redeployment, Major Mastromauro reported to Marine Corps Recruit Depot, Parris Island, South Carolina. He was assigned to Second Recruit Training Battalion and served as a Series Commander with Company F and a Company Commander with Company E. Major Mastromauro was then transferred to the Recruit Training Regiment and served as the Operations Officer.
In June 2015, Major Mastromauro reported to Expeditionary Warfare School in Quantico, Virginia.
In June 2016, Major Mastromauro reported to 3d Battalion, 11th Marines and assumed the duties of the Battalion Logistics Officer. In February 2017, Major Mastromauro was assigned as the Battery Commander of Battery K and deployed to support the Unit Deployment Program-Okinawa. Upon return from Okinawa, Major Mastromauro served as the Assistant Operations Officer.
In June 2018, Major Mastromauro reported to Marine Corps Training Mission-United Arab Emirates. He was assigned as a battalion-level advisor to the United Arab Emirates Presidential Guard.
In July 2019, Major Mastromauro reported to Marine Corps Command and Staff College. While attending, he earned a Masters of Military Studies.
In July 2020, Major Mastromauro reported to 3d Battalion, 11th Marines to serve as the Assistant Fire Support Coordinator. In May 2021, he assumed the duties of the Battalion Operations Officer. Then in September 2021, Major Mastromauro was assigned as the Battalion Executive Officer.
Major Mastromauro’s awards include the Navy and Marine Corps Commendation Medal (Two Gold Stars), Navy and Marine Corps Achievement Medal (One Gold Star), and the Combat Action Ribbon.