FOFEM - A First Order Fire Effects Model - is a computer program that was developed to meet needs of resource managers, planners, and analysts in predicting and planning for fire effects. Quantitative predictions of fire effects are needed for planning prescribed fires that best accomplish resource needs, for impact assessment, and for long-range planning and policy development. We have developed the computer program FOFEM to meet this information need. Much fire effects research has been conducted, but the results of this research have tended to be empirical, and thus limited in applicability to situations similar to those under which the research was conducted. Additionally, fire effects research results have not previously been assembled in a common format that is easily accessed and used, but rather have been scattered in a variety of journals and publications. In developing FOFEM, we have searched the fire effects literature for predictive algorithms useful to managers. These algorithms have been screened to evaluate their predictions over a range of conditions. We also determined the conditions under which each is best suited to use by examining the documentation of these algorithms. Thus, a major internal component of FOFEM is a decision key that selects the best available algorithm for the conditions specified by a user. In addition to selecting appropriate algorithms for users, we have also attempted to make these algorithms simple to apply; this has been done by incorporating the algorithms into an easy-to-use computer program. Realistic default values, documented in detail in this guide, have been provided for many inputs, minimizing the data required. These defaults were derived from a variety of research studies. Any of these default values can be overridden by the user, allowing the use of this program at different levels of resolution and knowledge. We anticipate that FOFEM will be useful in a variety of situations. Examples include: setting acceptable upper and lower fuel moistures for conducting prescribed burns; determining the number of acres that may be burned on a given day without exceeding particulate emission limits; assessing effects of wildfire; developing timber salvage guidelines following wildfire; and comparing expected outcomes of alternative actions. A new version, FOFEM6 replaces its two predecessors; FOFEM4 an IBM-PC DOS version developed in the early 1990s and FOFEM5 an IBM-PC Windows version developed circa 2000.