A very close collaborator of St. Ignatius of Loyola, the founder of the Society of Jesus, he was sent to explain to the various Jesuit communities of Europe the first draft of the Constitutions.

Born in Palma de Mallorca, in the Balearic Islands, on 11 August 1507, Jerome was the eldest of the four children of Antonio Nadal, a lawyer, and Maria Morey.

In the Latin Quarter he ran across Ignatius and his group of "friends in the Lord", including Peter Faber, Francis Xavier, and Diego Laynez.

In April 1536 he was ordained a priest by the auxiliary bishop of Avignon, Simon de Podio, and on 11 May he was awarded a doctorate in theology.

Ignatius quickly noticed his gifts and made him a trusted associate, a "contemplative in action", as Nadal would describe the Ignatian ideal.

At the General Congregation of 1558, which elected Diego Laynez as Ignatius' successor, as well as later, he was often consulted as being the one who, having been a very close collaborator with the Society's founder, best expressed his thoughts.

Shortly before Ignatius' death, he asked Nadal to oversee the project of producing engravings to facilitate these "contemplations" of Jesus in the Gospels.