A study examined the cognitive development of at-risk students (those who have experienced difficulty or failure in their careers as learners), focusing on such groups as potential drop-outs, minority children, and disabled students (dsylexic or non-English speaking), as well as teaching thinking to this same student population. Although research results on programmatic effects for at-risk students are somewhat controversial and frequently mixed, some guidelines for successful instruction are formulated, emphasizing interactive discussion during instruction. Teaching thinking involves not only learning cognitive skills such as analysis, classification, and evaluation, but also becoming conscious of the strategies that are appropriate to a particular task. The movement to teach thinking also focuses on the role of the teacher as a mediator of learning. Finally, the development of instructional materials and programs to teach thinking is being encouraged. Implications for the future include the need for teachers concerned with cognitive development, the need for long-term change as opposed to quick fix activities, the need for a better integrated curriculum, and the need to examine current policies and practices. (A total of 184 references are appended.) (MM)