Barry Turner’s 1978 Man-made Disasters and Charles Perrow’s 1984 Normal Accidents were seminal books but a detailed comparison has yet to be undertaken. Doing so is important to establish content and priority of key ideas underpinning contemporary safety science. Turner’s research found socio-technical and systemic patterns that meant that major organisational disasters could be foreseen and were preventable. Perrow’s macro-structuralist industry focus was on technologically deterministic but unpredictable and unpreventable ‘system’ accidents, particularly rare catastrophes. Andrew Hopkins and Nick Pidgeon respectively suggested that some prominent writers who wrote after Turner may not have been aware of, or didn’t properly acknowledge, Turner’s work. Normal Accidents didn’t cite Turner in 1984 or 1999. Using a methodology involving systematic reading and historical, biographical and thematic theory analysis, a detailed review of Turner’s and Perrow’s backgrounds and publications sheds new light on Turner’s priority and accomplishment, highlighting substantial similarities as well as clear differences. In a previously unpublished letter, Perrow confirmed reading Man-made Disasters while writing Normal Accidents. Turner became better known after a 1997 second edition but under-acknowledgment issues continued. Ethical citation and potential reasons for under-acknowledgment are discussed. It is concluded that Turner’s foundational importance for safety science should be better recognised.