Problem clarification and analysis are basic problem solving steps that address the fundamental question of what to change. The analysis of keystone child behaviors and other keystone events is a conceptual and research-based target variable selection strategy within the problem solving process. Keystone behaviors have been defined as (a) pivotal behaviors associated with response classes of maladaptive behaviors that can positively influence other child behaviors; (b) behaviors that result in other beneficial collateral child, peer, and adult outcomes; and (c) foundation skills necessary for adaptation to present and future environments. Stated differently, keystone variables represent relatively narrow targets for change having the most widespread benefits to clients. Within the context of ecological consultation and systems analysis, the term keystone variable, rather than behavior, is suggested because of the broad range of potential targets for efforts at permanent change and to acknowledge that such targets often go beyond presenting child problems. The hypothesized benefits of selecting keystone targets for change include more effective and efficient interventions.The design of interventions for childhood problems most often takes place through consultation with parents and teachers (Gutkin & Curtis, 1990;Kratochwill & Bergan, 1990). In consultation, the problem solving process leads the analysis of problem situations to the consideration of desired changes in parent, teacher, peer,The authors would like to thank Sabrina A. Petrelli for editorial assistance. The preparation of this manuscript was partially supported by a grant from the Ohio Department of Education, Division of Early Childhood.

The purpose of this report is to present the evaluation design and case study outcomes for 28 children from the first three years of the Ohio Early Childhood Intervention project (ECI). The ECI project was designed to help build the capacity of professionals for intervention design. Capacity building refers to preparing educational systems for change and, specific to this report, providing valid conceptual and procedural guidelines for early intervention. The foundations of the ECI project are ecobehavioral analysis, ecological consultation, and naturalistic intervention design. The acronym PASSKey (Planned Activity, Strategic Sampling, .Keystone behavior) describes three major aspects of the assessment-intervention guidelines. Validity evidence for the guidelines is based on single case quasi-experimental (accountability and case study) designs documented by comprehensive early childhood case portfolios. In addition, estimates were obtained of the consultants' time spent in problem solving.

This paper reviews applications, methods, research, and practice procedures for supporting intervention implementation through scripts. The recent emphasis in education on evidence-based practice and data-based programming suggests that intervention plans will become increasingly rigorous and scrutinized. Furthermore, research in applied behavior analysis suggests that many interventions are difficult to carry out in natural school settings without specific and often considerable support. Our focus is on young children. However, the methods to be described have broad applicability and could play an important role in multidisciplinary collaboration.

The purpose of this article was to present strategies for establishing meaningful and coherent goals for early intervention. First, from ecological theory, the natural and empirical bases of intervention design are reviewed, and the concept of fundamental units of analysis is explicated. Second, the idea of planned activities, which serve as natural units for intervention decisions, is presented. Third, aspects of sam-pling relevant for ecological interventions are discussed. Fourth, recommendations are made for using planned activities as a basis for sampling and intervention design. Being guided by planned activities may help resolve some controversial assessment questions and lead to stronger intervention plans, due to the emphasis on fundamental natural units of analysis.