Noting the lack of definitive information about teaching thinking skills and how they are implemented throughout the year or how they are coordinated among subject areas and articulated along grade levels, this booklet is intended to provide school districts with a successful plan for developing a comprehensive thinking program for grades K-12. The introduction to the booklet outlines six prerequisites for such a program, including a common vocabulary of thinking for all teachers, distinctions between process and product with regard to thinking, and an inservice program to acquaint teachers with the elements of the thinking instruction model. The first section of the booklet discusses conditions necessary for thinking--something to think about, something to think with, some ways in which to think, and something to think for. The next section then presents a five step model for developing a thinking program using the existing K-12 curriculum, and discusses major implications of this model for teaching and learning. The remaining sections of the booklet offer suggestions for implementing the model and for evaluating thinking. (HTH)