Democratic presidential nominee Hillary Clinton addresses the Democratic National Convention in Philadelphia on Thursday. (Toni L. Sandys/The Washington Post)

HILLARY CLINTON formally accepted the Democratic presidential nomination Thursday night, promising that “progress is possible” to unite a nation at a time when two-thirds of Americans say the country is on the wrong track. With many voters, and some candidates in both parties, calling for radical change to fix a “rigged” system of power, she insisted that “to drive real progress, you have to change both hearts and laws. You need both understanding and action.”

Ms. Clinton sought a balance between acknowledging Americans’ frustrations and rejecting undue pessimism. “There’s too much inequality, too little social mobility, too much paralysis in Washington, too many threats at home and abroad,” she said. “But just look for a minute at the strengths we bring as Americans to meet these challenges.” She depicted a nation “clear-eyed” about its problems but not in fear of them.

She rejected Donald Trump’s call to abandon the postwar leadership that has helped keep the peace in much of the world. The nation needs “a leader who understands we are stronger when we work with our allies around the world”

She also insisted that she could make progress in Washington, despite the gridlock and division of recent years. Undermining political institutions may feel satisfying to those who believe they have been mistreated or abandoned by the existing system, but true change can come only through persistent effort applied within the country’s democratic system, which, from the days of the Founding Fathers, has required compromise, she argued.

Ms. Clinton sought to turn her long years on the public stage from a potential handicap in this anti-establishment year to an advantage. “It’s true, I sweat the details of policy — whether we’re talking about the exact level of lead in the drinking water in Flint, Michigan, the number of mental health facilities in Iowa, or the cost of your prescription drugs,” she said. From working on the impeachment of President Nixon to eight turbulent years as the nation’s first lady, to service in the Senate and in President Obama’s Cabinet, she could honestly brag that, when in office, she won respect from her political rivals. “I’ve worked across party lines to pass laws and treaties and to launch new programs that help millions of people,” she said. “And if you give me the chance, that’s what I’ll do as president.”

She also struck a balance as she acknowledged the history she made this week, without arguing that she deserves votes simply for being a woman. “Tonight, we’ve reached a milestone in our nation’s march toward a more perfect union: The first time that a major party has nominated a woman for president,” she said, describing a moment “for boys and men — because when any barrier falls in America, it clears the way for everyone.”

Ms. Clinton generously saluted her primary rival, Sen. Bernie Sanders (I-Vt.), who has promised to work for her election. She has adopted some of his positions and rhetoric, but Thursday night she made clear that her vision of how change happens has not shifted to his belief in political revolution. Change comes “step-by-step, year-by-year . . . sometimes even door-by-door,” she said. Her challenge between now and November will be to persuade voters that a promise of such incremental progress is more attractive than the reckless and fact-free leadership offered by her opponent.