Dr. Rolf first called her work Personal Structural Integration and formed a Guild for the practitioners she taught. In the 1960s she was working and teaching at the Esalen Institute at Big Sur in California. The Esalen Institute at that time was the hub of the human potential movement where people were exploring new ideas such as eastern philosophy, yoga, meditation, Gestalt etc, ideas which are now part of the common discourse.
At that time those exploring these new ideas were on the margins and were not all that respectful of conventions. They began to describe the experience they had while Dr. Rolf was working on them as having been Rolfed, apparently Dr. Rolf was none too gentle and they really felt worked over but in a good way. Dr. Rolf at first resisted this informality but eventually softened, realizing that it was more of a compliment than an impertinence and began to use the terminology herself. In 1972 she opened the Rolf Institute for Structural Integration in Boulder Colorado and the terms Rolfer® and Rolfing® were registered as service marks of the Rolf Institute. Now in order to legally call oneself a Rolfer® or describe what they do as Rolfing® they must have trained at the Rolf Institute.
In 1990 several of the senior teachers and administrators of the Rolf Institute left and reformed the Guild for Structural Integration in order to maintain the purity of Dr. Rolf’s teaching of the basic ten series recipe. Graduates of the Guild or any of the several other schools which teach the ten series call themselves Practitioners of Structural Integration. So Rolfing® is a term specific to one institution while Structural Integration is a more descriptive and generic term.