The extraordinary story of Margaret O’Shaughnessy Heckler offers a rare view into the behind-the-scenes world of American politics from the 1960s through the 1980s. Her career spanned five presidencies: Johnson, Nixon, Ford, Carter, and Reagan. The daughter of Irish immigrants, Margaret Heckler represented the American dream. She served as a congresswoman, a presidential cabinet secretary, and an ambassador—all groundbreaking achievements for a woman of her era. The fiery Irish Republican (R-MA) mastered the seemingly unbeatable game of being a woman in a man’s world and a Republican in a Democratic state, becoming a champion for others against all odds. Heckler was the only newly elected woman appointed to Congress in 1966, entering rooms where few women were invited before. Her landmark legislation, the Equal Credit Opportunity Act, gave women the right to credit in their own names for the first time in American history. She also convinced presidential nominee Ronald Reagan to appoint the first woman Supreme Court Justice, Sandra Day O’Connor. As President Reagan’s Health and Human Services Secretary, Heckler was one of the most powerful women in America, responsible for the third-largest budget in the world. She took the lead in addressing the AIDS crisis and commissioned the Heckler Report to address racial inequities in health care. She was later appointed by Reagan as the first female ambassador to Ireland, a highly sought-after diplomatic post. A Woman of Firsts is a tribute to a woman who helped break the glass ceiling and fought to provide equality and justice for millions of Americans.