Born Ruckstuhl in Breitenbach, Alsace, France, his family moved to St. Louis, Missouri in 1855. He worked at a variety of unsatisfying jobs until his early twenties when an art exhibition in St. Louis inspired him to become a sculptor. He studied art locally, visited Paris and then worked for years as a toy store clerk to save enough to study in Paris for three years.
In 1885, Ruckstull entered the Académie Julian, and studied under Gustave Boulanger, Camille Lefèvre, Jean Dampt and Antonin Mercié. He considered studying with Auguste Rodin, but claimed to be disgusted with his style.
Ruckstull was a founding member of the National Sculpture Society as well as the editor of the magazine Art World. In 1925 he wrote the book Great Works of Art and What Makes Them Great, a collection of essays he had published previously [ISBN 0-7661-7108-6]. It has recently been reprinted.
His sculpture was in the figurative Beaux-Arts style, with its realism, and detailed modeling. He and other prominent sculptors of the era such as Daniel Chester French championed the French style of studio system teaching, art societies, and exhibitions.
He married in 1896 and had one son. Following the Armory Show of 1913, he continued to represent the old guard of academic sculpture. This perspective is clearly expressed in Ruckstull's 1925 book, "Great Works of Art - And What Makes Them Great." He died in New York at the age of 89 and was cremated.