Mr. Monks thinks that needs to change.

“It’s critical that mutual fund investors require the trustees of their accounts to act like stewards of each company they hold in their portfolio,” he said. “Many mutual fund companies are equipped to do this.” Those that aren’t should be responsive when researchers point out current problems. “When a corporate governance issue comes to light,” he said, “they need to be involved.”

HE also contends that others among the nation’s biggest investors — charitable funds and endowments — need to play more active roles. In his book, he argued that if excessive executive pay was to be curbed, it was important that the trustees of the top dozen endowments and charitable funds, accounting for $200 billion in collective assets, actively take a stand. “These are flesh-and-blood individuals who can actually do something,” he said.

Mr. Monks comes from a patrician New England background. With his wife, Millicent — a great-granddaughter of Thomas Carnegie, the younger brother of Andrew Carnegie — he lives on a private island off the coast of Maine, from which he wages his battles against today’s corporate titans.

A self-described education snob, highly attuned to the background and credentials of those he meets, he earned a bachelor’s degree at Harvard, did graduate work at Cambridge in Britain and then returned to Harvard for his law degree.

He sees himself as one of the last of the Rockefeller Republicans, and he served as a co-chairman of Republicans for Obama in Maine during the 2008 presidential election. During that campaign, he entertained Barack Obama at his home.

Mr. Monks even had political ambitions of his own. In 1972, 1976 and 1996, he ran unsuccessfully for the United States Senate. During his first race, he said, he had an epiphany that eventually set him on the path of corporate governance reform. While staying at a hotel on the bank of the Penobscot River, he says, he saw a wall of white foam coming down the river. He learned that it came from the paper companies in the area.

After that election, he became chairman of a trust company with paper company holdings. Mr. Monks said he wrote letters urging these companies to improve their environmental practices. The Clean Water Act of 1972 and its various amendments eventually provided the impetus for a significant cleanup of the river.