About 100 activists and supporters took up residence in the two-story commercial structure, believed to be a former music building of nearby Sacred Heart Cathedral High School and located within sight of archdiocesan headquarters at St. Mary's Cathedral.
Police, who had monitored the protesters' actions all day, stood by as protesters entered the building, which had already been opened by other activists. Police spokesman Sgt. Michael Andraychak said the department was "still talking" to the building's owner to determine the next step.
Reached late Sunday, archdiocesan spokesman George Wesolek said church officials had decided to ask police not to take any immediate action.
"We will revisit the situation in the morning," he said.
The well-organized takeover of the structure is the first major undertaking by the Occupy movement in San Francisco since protesters' encampment on the Embarcadero was cleared out by police in December.