On the second stop of his three-nation tour of South America, the pope addressed the throng in the vast Christ the Redeemer Plaza in Santa Cruz, including many people who camped out overnight to see him.
He denounced what he called a "mentality in which everything has a price, everything can be bought, everything is negotiable. This way of thinking has room only for a select few."
"Jesus speaks these words to us, here in this square. No one has to be discarded," the 78-year-old pontiff, the first pope from Latin America, told the crowd, estimated by Bolivian authorities at one million strong.
The two-hour service featured religious hymns and chants. Hundreds of musicians also played Baroque works, introduced by Spanish Jesuit missionaries in the 18th century and still very popular in this country.
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Thousands in the crowd were from Bolivia's indigenous majority: Quechua, Guarani and Aymara Indians. President Evo Morales, the country's first indigenous leader, was in the front row.
Around the plaza, dominated by the giant bronze Christ the Redeemer statue, big-screen TVs were erected for people to watch the religious service.
Since his election in 2013, Francis -- who hails from Argentina and is also the first Jesuit pope -- has indeed shown himself to have a down-to-earth air about him, and that is ringing clear in Santa Cruz.
Many people spent the night in the plaza to get a spot for mass and a good view of the pontiff. The weather was unseasonably chilly, but was expected to warm as the day progressed.
"We want to be as close as possible to receive the blessings that he is going to bestow," said one of the happy campers, Nancy Camacho, her head wrapped in a thick scarf, before the service started.