Frances Moore Lappé (born February 10, 1944) is an American researcher and author in the field of food and democracy policy. She is the author of 20 books including the 2.5-million-copy selling 1971 book Diet for a Small Planet, which the Smithsonian's National Museum of American History describes as "one of the most influential political tracts of the times." She has co-founded three organizations that explore the roots of hunger, poverty, and environmental crises, as well as solutions emerging worldwide through what she calls "living democracy". Her latest work is a report entitled Crisis of Trust: How Can Democracies Protect Against Dangerous Lies? with Max Boland and Rachel Madison. Recent books by Lappé include Daring Democracy: Igniting Power, Meaning, and Connection for the America We Want, co-authored with Adam Eichen, and It's Not Too Late: Crisis, Opportunity, and the Power of Hope. In 1987, she was awarded the Right Livelihood Award for "revealing the political and economic causes of world hunger and how citizens can help to remedy them."

Lappé was born in 1944 in Pendleton, Oregon, to John and Ina Moore and grew up in Fort Worth, Texas. After graduating from Earlham College in 1966, she married toxicologist and environmentalist Dr. Marc Lappé in 1967. They have two children, Anthony and Anna Lappé. She briefly attended University of California at Berkeley for graduate studies in social work.

"Over the years many people have been surprised when meeting the author of Diet for a Small Planet. I am not the gray-haired matron they expect. Nor am I a back-to-nature purist. (Sometimes I even wear lipstick!) But mouths really drop open when I explain that I am not a vegetarian. Over the last ten years I've hardly ever served or eaten meat, but I try hard to distinguish what I advocate from what people think of as 'vegetarianism'... what I advocate is a return to the traditional diet on which our bodies evolved. Traditionally the human diet has centered on plant foods, with animal foods playing a supplementary role. Our digestive and metabolic systems evolved over millions of years on such a diet. Only very recently have Americans, and people in some other industrial countries, begun to center their diets on meat. So it is the meat-centered diet-and certainly the grain-fed-meat centered diet-that is the fad."

Throughout her works Lappé has argued that world hunger is caused not by the lack of food but rather by the inability of hungry people to gain access to the abundance of food that exists in the world and/or food-producing resources because they are simply too poor. She has posited that our current "thin democracy" creates a maldistribution of power and resources that inevitably creates waste and an artificial scarcity of the essentials for sustainable living.

Lappé makes the argument that what she calls "living democracy", i.e., democracy understood as a way of life, is not merely a structure of government. The three conditions essential for democracy, she writes in Daring Democracy and elsewhere, are the wide dispersion of power, transparency in public affairs, and a culture of mutual accountability, not blaming. These three conditions enable humans to experience a sense of agency, meaning, and connection, which she describes as the essence of human dignity. Democracy is not only what we do in the voting booth but involves our daily choices of what we buy and how we live. She believes that only by "living democracy" can we effectively solve today's social and environmental crises.

Lappé began her writing career early in life. She first gained prominence in the early 1970s with the publication of her book Diet for a Small Planet, which has sold 2.5 million copies.

In 1975, with Joseph Collins, she launched the California-based Institute for Food and Development Policy (Food First) to educate Americans about the causes of world hunger. In 1990, Lappé co-founded the Center for Living Democracy, a nine-year initiative to accelerate the spread of democratic innovations in which regular citizens contribute to problem-solving. She served as founding editor of the center's American News Service (1995–2000), which placed stories of citizen problem-solving in nearly half the nation's largest newspapers.

In 2002, Lappé and her daughter Anna established the Small Planet Institute based in Cambridge, Massachusetts, a collaborative network for research and popular education to bring democracy to life. With her daughter, she traveled the world and wrote Hope's Edge. The two also co-founded the Small Planet Fund, channeling resources to democratic social movements worldwide.