Eagle Star grew up on the Rosebud Indian Reservation in South Dakota. From November 1882 until 1888, he attended the Carlisle Indian Industrial School (CIIS) in Carlisle, Pennsylvania. In 1889, Eagle Star returned to the Rosebud Agency and began working in a blacksmith shop alongside fellow former CIIS student Frank Locke; during this time, it is also speculated that Eagle Star may have been a member of the Rosebud Indian Police. According to a correspondence between Oglala Sioux George Means and Captain R. H. Pratt, Eagle Star traveled to the Pine Ridge Indian Reservation during the Battle of Wounded Knee, but did not take part in the fighting.