Nassau County police say Patricia Adams, 46, reached over a pew and took cash from a purse while its owner knelt Sunday at Our Lady of Hope Roman Catholic Church in Westbury.
Police say an usher saw the theft, and officers stopped Adams as she left the church.
Police say they determined the same woman stole cash from another worshipper's purse while that victim took communion on Mother's Day.
Adams has been released on an appearance ticket after being arrested on petit larceny charges. She faces up to a year in jail if convicted.