Stratigraphic forward modeling and comparison with published case studies have been used to determine the controls and stability domains of two conceptual models concerning relative sea-level fall in carbonate sequence stratigraphy. In the standard model, deposition occurs principally during rise and stillstands of relative sea level; a continuous erosional unconformity develops during sea-level fall. The falling-stage systems tract model (FST) postulates significant deposition during sea-level fall. Sedimentological principles, numerical models and published case studies of tropical carbonate sequences indicate that presence or absence of FST is not simply a function of the rate of sea-level fall but depends on the balance of the rates of erosion, sea-level fall and carbonate production, whereby the FST is favoured by high production, slow erosion and slow sea-level fall. Case studies plotted in the parameter space spanned by these variables support the modeling results. The ranges of rates required for the FST in the modeling runs are common in the geologic record. Consequently, the FST can be expected to be more common in tropical carbonate rocks than published records, particularly seismic data, currently indicate. © 2009 The Authors Journal compilation © 2009 Blackwell Publishing Ltd, European Association of Geoscientists & Engineers and International Association of Sedimentologists.