In 1836, Dr. Willard Richards worked at a medical practice in Boston, Massachusetts when he came across The Book of Mormon. He read the book twice within ten days and, after making the necessary preparations, left for Kirtland, Ohio to join the Church and be with the Saints. Richards was baptized there on December 31, 1836, by Brigham Young and ordained an Elder roughly two months later, in February 1837.

Shortly following his ordination, Richards was called on a brief three-month mission to the Eastern United States. He was called on a more extended mission to Great Britain immediately upon his return. Richards met his wife, Jennetta Richards, while thusly engaged.

He was ordained an Apostle on April 14, 1840 by Brigham Young.

Richards was a member of the incarcerated party at Carthage Jail when Joseph Smith, Jr. and Hyrum Smith were martyred.

After the death of Joseph Smith, he was called as Second Counselor in the First Presidency under Brigham Young.

Reference