In 1970 an evaluation of a national textbook program implemented by the Ministry of Education of Ecuador was carried out. The pre and post test design involved three treatment types: 1) classrooms with new textbooks, guides and orientation to teachers in the new textbook programs; 2) classrooms with new textbooks and guides but no teacher orientation; and 3) classrooms with other, or no, textbooks, and no teacher orientation. The design was field experimental with treatments assigned to particular schools. Findings, discussed and summarized, indicate that only the subject area of reading showed a significant interaction. Several significant differences between school types (graded, multi-graded and ungraded) were revealed by analysis. Only one out of nine comparisons was significant among the three field experimental conditions, with classrooms with new texts and no orientation having the smallest reading gains. Variables in the change process are identified in the discussion section and theories of adoption of change are related to the findings. References and supporting data are included in the report. (Author/KSM)