"All that is beautiful leads us to God," Francis said on Saturday evening, at an event emceed by actor Mark Wahlberg.
The pontiff spoke in Spanish and paused at each line to let an English translator chime in.
"Love is celebration. Love is joy. Love is moving forward," the Pope said.
Calling families "a factory of hope," Francis drew laughs from the crowd as he acknowledged his message might be greeted with skepticism by some.
"Father, you speak like that because you're not married," a skeptic might say, he said. "Families have difficulties. In families we quarrel. Sometimes, plates can fly. Children cause headaches. I won't speak of mother-in-laws.
"But," the Pope added, "in families, there is always light."
He offered advice to families who fight from time to time: "Never let the day end without making peace."
Before the Pope spoke, families from different countries shared with him and the audience the stories of their struggles, triumphs and values -- emphasizing a central message: the strength of following their faith and sticking together.
A father from Jordan talked about facing religious persecution and the push to help refugees. A grandfather from Argentina talked about the challenges of being an immigrant. A mother from Nigeria spoke of the difficulty her family faced after her first daughter died.
In addition to stories of struggle, there were joyous moments.
As Queen of Soul Aretha Franklin belted out "Amazing Grace," Francis smiled and clapped to the beat.
And after hearing the families' stories, a beaming Pope thanked them, saying they were "a real witness that it is worth having a family."
The crowd roared with applause and cheers.
Diane Hoffman, 48, said afterward that the Pope's words resonated with her as she tries to be a good mom to her 3-year-old and 4-year-old.
"I thought they were inspiring and they were for me personally encouraging, for my family. I need to put in more effort and to remember love is the base of everything," said Hoffman, who lives outside Philadelphia.
Patrick Moiani, a 26-year-old audiovisual service technician who attended the event with his brother, sister-in-law and nephew, said it was clear from the way the crowd cheered that the Pope's message reached his audience.
"He focused on the positives of bringing people together," he said. "You could feel the energy."
Alberto Espinoza Chavira, a 55-year-old sales agent from Chihuahua, Mexico, said he waited outside for 12 hours for a chance to see the Pope. And it was well worth it.
"He showed us that we should not be afraid to love each other," he said, "and to apologize to each other as a family."