Issues pertaining to thinking skills are discussed in an attempt to clarify what thinking skills are and their components, how they function and how they can be developed in the teaching-learning environment. Chapter 1 reviews the definitions of thinking skills. These definitions are selected from the current literature on education and psychology. Chapter 2 provides a national perspective on the implementation of thinking skills programs. Chapter 3 describes a variety of programs in Oregon elementary and middle schools. Three commercial thinking skills programs are described in chapter 4. Chapter 5 discusses some criteria that can be used when designing or selecting thinking skills programs. The bulletin concludes that the multidimensionality involved in the teaching of thinking skills and the unidimensionality entailed in defining and measuring them through standardized tests run counter to one another. Students can learn to apply their thinking skills in the real world if textbook problems sufficiently resemble real-world problems; that is, textbook problems should be contextualized. (SI)