Joseph H. Gainer holds a strong educational background, having graduated from LaSalle Academy and the College of the Holy Cross before earning a law degree from the Catholic University of America. He began his career in public service early, being elected to the Providence School Committee in 1902. Gainer's political career advanced rapidly, as he became a councilman, alderman, and eventually mayor of Providence at age 34, making him the youngest mayor in the city's history at the time. His leadership roles extended to national politics, serving as a delegate to the 1916 Democratic National Convention. Throughout his career, Gainer demonstrated a commitment to public service and progressive governance.

Joseph H. Gainer's political identity is marked by an intriguing blend of progressive economic policies and a steadfast dedication to local governance. His early involvement in the Providence School Committee and subsequent roles in local government reveal a deeply rooted commitment to community-focused leadership. Gainer's unexpected convergence with opposing factions on environmental regulations during his mayoral tenure suggests a highly localized approach, balancing industrial interests with broader public welfare. His ideological agility, seen in both his progressive economic stances and his active participation in the Democratic Party, underscores a nuanced political philosophy that challenges conventional party lines.