Over the past decade educational researchers and curriculum evaluators have dealt with the deviation between a specified educational program and its actual implementation. These differences have been referred to as a critical problem in both the achievement and the evaluation of a program's goals. The research reported here has explored the grassroots implementation of computer-use in classrooms as an alternative approach to program implementation. An ethnographic study of six exemplary elementary classrooms in the San Diego County (California) area found that successful implementation of computers was the result of the combined efforts of an enthusiastic teacher, who became the "computer expert," and a supportive principal, who in most cases did not know about computers but recognized their potential. These implementation efforts resulted in applications that were different from conventional uses, and were evaluated against heterogeneous criteria of success. Diversity in the implementation of computers in education was found to be a useful mechanism for coping with the rapid rate of change in computer technology. The grassroots introduction of computers required extensive efforts on the part of the teachers involved and resulted in the recognition of their academic effort by colleagues. If the implementation of computers had followed the traditional top-down hierarchical approach, it could not have kept abreast of rapid technological changes and might have become overly constrained in its application. (23 references) (Author/GL)