VATICAN CITY — Pope Francis created 21 new cardinals Saturday, including key figures at the Vatican and in the field who will help enact his reforms and cement his legacy as he enters a crucial new phase in running the Catholic Church.

With Saturday’s additions, nearly three-quarters of the voting-age “princes of the church” owe their red hats to the Argentine Jesuit.

In his instructions to the new cardinals at the start of the service at St. Peter’s Square, Francis said their variety and geographic diversity would serve the church like musicians in an orchestra, where sometimes they play solos, sometimes as an ensemble.

“Diversity is necessary; it is indispensable. However, each sound must contribute to the common design,” Francis told them. “Each musician must listen to the others.”

Among the new cardinals was the controversial new head of the Vatican’s doctrine office, Victor Manuel Fernandez, and the Chicago-born missionary now responsible for vetting bishop candidates around the globe, Robert Prevost.

Also entering the exclusive club were the Vatican’s ambassadors to the United States and Italy, two important diplomatic posts where the Holy See has a keen interest in reforming the church hierarchy. Leaders of the church in geopolitical hotspots like Hong Kong and Jerusalem, fragile communities like Juba, South Sudan, and sentimental favorites like Cordoba, Argentina, filled out the roster.

Francis’ promotions of Prevost and his ambassador to Washington, French Cardinal Christophe Pierre, were clear signs that he has his eye on shifting the balance of power in the U.S. hierarchy, where some conservative bishops have strongly resisted his reforms.

“I think I do have some insights into the church in the United States,” Prevost said after the ceremony.