With this issue, the Forum begins a series of articles devoted to the topic of the functional assessment of behavior. Additional articles in the series will be published in subsequent issues of the journal. The articles were submitted and reviewed as a set under the leadership of Ron Nelson and his colleagues, of Arizona State University. We are grateful to them for inviting a series of articles on a topic that deserves particularly careful scrutiny at this point in our professional history. Functional behavioral assessment is an issue of special importance today because it is mandated by the 1997 amendments to the Individuals with Disabilities Education Act (IDEA) (see Bateman & Linden, 1998; Yell, 1998; Yell & Shriner, 1997 for details). Yell summarized the requirements of IDEA 1997 in language clearer than that found in most laws: To deal with behavioral problems in a proactive manner, the 1997 amendments require that if a student with disabilities has behavior problems (regardless of the student's disability category), the IEP [individualized education program] team shall consider strategies-including positive behavioral interventions, strategies, and supports-to address these problems. In such situations a proactive behavior management plan, based on functional behavioral assessment, should be included in the student's IEP. Furthermore, if a student's placement is changed following a behavioral incident and the IEP does not contain a behavioral intervention plan, a functional behavioral assessment and a behavioral plan must be completed no later than 10 days after changing the placement. (1998, p. 88, emphasis not in original). By definition, all students with emotional or behavioral disorders exhibit behavior problems. A high percentage of those in other categories of disability do as well, particularly those categorized as having learning disabilities or mild mental retardation as their primary disability. It follows that functional behavioral assessment, whatever the meaning of the term, is now very much a part of our business as special educators, especially if we serve students with emotional or behavioral disorders. IDEA 1997 is clear on this: A functional behavioral assessment should be included in the IEP of every student who exhibits serious behavior problems. Not clear, however, are answers to two questions: First, what was the intention of those who wrote the law (i.e., what is the legal meaning of the term)? Second, what does functional behavioral assessment mean to educators and related service providers? Clearly, the term may mean different things to different people, and it is not well understood by most educators. To the knowledgeable special educator or psychologist, functional behavioral assessment involves a set of procedures that are a sophisticated part of applied behavior analysis. In fact, it is possible--even likely-that a graduate course in applied behavior analysis may not prepare students to complete a functional behavioral assessment as envisioned by those who have done research on functional behavioral analysis. Prior to studying the functional assessment of behavior, students need to acquire skills in pinpointing behavior, collecting and graphing direct observation data, implementing and interpreting the data obtained in single-case experimental designs, and regulating consequences to alter behavioral trajectories. …