Jerry (Jeremiah ; Jerome) O’Brien, a button accordion player from Kinsale, County Cork, helped shape Irish traditional music in Boston. Raised in Ireland, he likely learned to dance in Ireland, although it appears unlikely he played the accordion before emigrating. In 1921, political circumstances drove him away from Ireland. In Boston, O’Brien and his brother Timothy were active members of the Irish Pipers Band of Boston, an organization whose members performed on píb mhór, staged military-style drill exhibitions and promoted Irish cultural nationalism through public events and feiseanna. In 1925, O’Brien joined the Celtic Harmony Club under the leadership of Joe O’Leary, who made O’Brien a featured performer on his radio show. He was also a frontline member of O’Leary’s Irish Minstrels, O’Leary’s band that made recordings for Columbia Records. O’Brien made two solo sides as part of the group. From the early 1930s into the 1950s, O’Brien maintained a close relationship with Justus O’Byrne DeWitt. In 1934, he performed on DeWitt’s cruises to Ireland and later worked in his music shop as a clerk and instructor, producing instructional publications and mentoring Joe Derrane. During this period, O’Brien also recorded for Copley Records as both a soloist and ensemble member.