Five large-scale fire tests were conducted to determine sprinkler protection requirements for non-storage occupancies with floor-to-ceiling clearance up to 18.3 m. Examples of high-ceiling, non-storage occupancies are atrium spaces, movie theaters/studios, auditoriums, and some selected manufacturing facilities. The fire tests were conducted at a 18.3-m high test site using fuel arrays that were designed to simulate ordinary hazard fire scenarios. Sprinkler protection parameters and fuel arrangements were varied in the tests. The tests showed that:1) the sprinklers would provide adequate protection for these occupancies despite a clearance as high as 16.6 m from the top of the fuel stacks to the ceiling, 2) protection based on a 12-mm/min discharge density over a 465-m2 demand area was judged adequate for fire hazards equivalent to a FMRC Class 3 Commodity, 3) protection based on a 6-mm/min discharge density over a 232-m2demand area was adequate for fire hazards up to a Class 2 Commodity, 4) protection based on QR-ELO sprinklers delivering a 18-mm/min discharge density over a 232-m2demand area would provide adequate protection for high-ceiling occupancies exposed to a limited amount of plastic materials. Sprinkler skipping, extended sprinkler spacing, and protection of occupancy with a ceiling higher than 18.3 m remain as subjects needing further study.