Years later, in October 1843, Pratt recommended to Joseph Smith that the Church begin missionary work among the Polynesians, whom he expected to be receptive.

Smith sent Pratt, Benjamin Franklin Grouard, Noah Rogers and Knowlton F. Hanks to create a mission in the Pacific Islands.

Pratt disembarked at Tubuai in the Austral Islands on April 30, 1844, and began teaching in the Hawaiian language, noting its similarity to the local dialect of Tahitian.

His wife Louisa was called to serve a mission with him and went from Utah to San Francisco with a group of LDS missionaries heading to Hawaii in 1850.

In May 1852, the French government restricted the preaching of Mormonism in the islands, and Pratt and his family were held under house arrest until they eventually were able to return to California.

Pratt declined invitations from church leaders and entreaties of his wife Louisa to follow the practice of plural marriage.

Pratt's journal chronicles this time period, including his interactions with Samuel Brannan and members of the Donner Party.

After the Donner Party tragedy the year before, Pratt elected to pursue an alternate route over the Sierras when traveling eastward to Salt Lake City.