Built at an unknown date between 1792 and 1809, it was located approximately five miles from the main mission, inland and upstream along the Ventura River.

A number of foundation stones were moved and used to create the Santa Gertrudis Asistencia Monument which was designated in 1970 as Ventura County Historic Landmark No.

The asistencia was built along the route of El Camino Real, a historical trail that linked California's Spanish missions.

There at the point where the Casitas Pass road branches from the road to Ojai, stood their own sacred tree - a great sycamore under whose wide-spread boughs they had always assembled to worship their primeval god, and amongst whose leaves, even down to modern times, they used to hang their offerings of gay feathers and bright cloth and the skins of animals.

"[7][8] The second relocation followed the 1812 San Juan Capistrano earthquake when the padres moved inland and remained for several months until the Mission was repaired.

Although the historical record is unclear as to whether Santa Gertrudis was the site of refuge, historian E. M. Sheridan wrote as follows in an unpublished account: "Miguel was put in charge of the advance guard of Indians to head northward and make arrangements for the reception at Casitas, at the Chapel of Santa Gertrudis which was considered far enough back as to become an abiding place until Bouchard and the expected pirates should have come and gone.

[16] During the 1966 excavation, the location of the asistencia was determined through the use of an 1853 map of Rancho Cañada Larga o Verde discovered at the Bancroft Library in Berkeley, California.

The foundation was built using large sandstone boulders believed to have been carried from the nearby Ventura River and placed in trenches.

"[20] Greenwood and Browne further observed that the removal of the roof tiles was consistent with historical accounts of rapid and total disintegration of the adobe in the years that followed.

[2] Following the findings of the archaeological survey, many individuals and groups advocated for the relocation and restoration of the chapel, but no plan was adopted prior to the freeway's construction.