Fire-frequency (FF) analysis is used to derive, from empirical data, parameters that describe the frequency of fires in a system; the time-since-fire distribution; the age-specific probability of fire; and other summary statistics such as the natural fire rotation, the mean fire-return interval, and the fire cycle (Heinselman 1973, 1981; Romme 1981; Agee 1993; Johnson and Gutsell 1994). Results of FF analyses have been used to identify changes in conditions affecting fires in the past (Heinselman 1973; Alexander 1980; Stokes and Dieterich 1981; Hemstrom and Franklin 1982; Mastrogiuseppe et al. 1983; Johnson et al. 1990; Johnson and Larsen 1991; McCune 1983; Romme 1982; Swetnam 1993), to model landscapes produced by natural or altered fire regimes (Baker 1992), and to predict the amount of old forests expected in natural fire-dominated landscapes (B.C. Ministry of Forests and B.C. Environment 1995; Johnson et al. 1995; Martell 1995; Lesica 1996). The ecosystem-management paradigm of mimicking natural disturbances in managed ecosystems (Hunter 1993; Grumbine 1994) or containing the effects of management within the range of natural disturbances (Attiwill 1994) has recently increased the influence of FF models in informing planning decisions in forest management (Mutch et al. 1993; B.C. Ministry of Forests and B.C. Environment 1995) and in protected areas management (Brown et al. 1995). Unfortunately, a common method of applying empirical data on stand ages to FF analysis is incorrect, producing incorrect results and interpretations in published studies. We demonstrate the mistake by examining the derivation of FF models, comparing them to their analogue in population ecology, static life-table (SLT) analyses.