Areally widespread, predominantly shallow-water carbonates of the Cooking Lake Formation of Late Devonian age provided a platform on which isolated Leduc reefs grew in east-central Alberta. This study centres on the investigation of these platformal carbonates in the vicinity of the Redwater reef complex, a large isolated subsurface Leduc buildup, and focuses on the interrelationship between platform evolution and reef inception and localization. Cooking Lake deposition commenced during a progradational phase corresponding to a lowering of relative sea level. The ensuing platform succession consists of eight major cycles, each approximately 10 m thick. During platform evolution, a broad area of peritidal carbonate accumulation, corresponding to the lower part of the Cooking Lake Formation, developed into a number of more areally restricted shallow-water shoals. This evolution records the interactive influences of relative sea-level rises, variable organic growth potential and changes in seafloor topography on patterns of carbonate sedimentation. By the end of Cooking Lake deposition, one of these paleotopographic highs, the Redwater Shoal, approximately 30 km across, bordered two connected, relatively deep-water reentrants, with water depths of at least 25 m. The more windward northeastern and northwestward sides of this shoal, facing the deep-water reentrants, were relatively steep, whereas the leeward southern side gradually sloped into water depths of approximately 10 m in a ramp-like manner. A relative sea-level rise following the development of this paleotopographic high initiated Leduc reef growth on the Redwater Shoal. Lower-lying areas surrounding the shoal were drowned and ultimately became the sites for basinal carbonate accumulation. Preceding sea-level rises of a similar magnitude, but predating pronounced platform-shoal development, did not result in localized shallow-water (reefal) deposition, but merely initiated new cycles of widespread platform sedimentation.