Social Venture Network. Business for Social Responsibility. Net Impact. Grameen Telecom. Some of the most well-known names in progressive and socially-responsible businesses share a common touchpoint: Josh Mailman. Son of the late Joseph Mailman, founder of a knife and razor company that grew into the conglomerate Mailman Corporation, Josh emulates his father’s entrepreneurial (and philanthropic) spirit—always on the lookout for the next big idea.

For the younger Mailman, social activism is a natural outgrowth of political activism in the 1960s and 70s. That activism defines his philanthropy to this day. “I back agitators, instigators, and organizers,” says Mailman. “Those are the people that get stuff done.”

Mailman is a trailblazer in impact investing, having provided seed money for Stonyfield Farms, Seventh Generation, and dozens of other successful, socially-minded businesses. Meanwhile, he’s been a major proponent of corporate social responsibility. As founder of the Threshold Foundation, Mailman has rallied other philanthropists to join him in building movements to change the world.

Mailman’s philanthropic purview is simultaneously local and global, from Grameen Phone in Bangladesh, to the Middle East, where he proposed a Muslim version of the MacArthur genius awards, to supporting native peoples and communities. All of these disparate investments share a common thread: Mailman’s strong commitment to like-minded “activist entrepreneurs” like himself.