After the death of Joseph Smith, Aldrich went on to lead a small denomination of Latter Day Saints known as the Brewsterites.

In April or May 1832, Aldrich was taught about the Latter Day Saint movement by missionaries Orson Pratt and Lyman E. Johnson and was baptized in Bath, New Hampshire.

On September 29, 1849, Aldrich became the president of this Latter Day Saint denomination, and edited a Brewsterite periodical entitled the Olive Branch.

In August 1850, Brewster led about 85 of his followers (including Hazen Aldrich's pregnant daughter, Betsy Aldrich Wilder and her family) from Independence, Missouri, to the edenic "Land of Bashan" that Brewster had seen in visions, lying at the confluence of the Gila and Colorado rivers, in the southwestern United States.

[1] Aldrich, who did not follow Brewster to Arizona, resigned his position as church president in January 1853, and emigrated to California to support his daughter Betsy through her divorce, and to live with his other daughter, Louisa Aldrich Geary and her family, in El Monte, Los Angeles, California.