The first section of this article examines the historical record of Ohio's Second Constitutional Convention in an effort to discern what the delegates meant by "thorough and efficient" system of education. Included in this analysis are other historical documents that give further indication of the intent of the delegates. A brief review of the record in other states that adopted the "thorough and efficient" standard concludes the section. The second section of this article analyzes recent judicial interpretations of the phrase. It will be shown that there are widely varying understandings of "thorough and efficient" among the various state courts. These variations are significant because the historical record indicates that the constitutional framers in the states with the "thorough and efficient" standard used the same words intending to convey the same meaning. Thus, the varying modern judicial interpretations cannot be justified; at least some of these readings of "thorough and efficient" fail to properly construe the education standard. The third section of this article evaluates the modern judicial interpretations of "thorough and efficient" against the historical record of Ohio's Second Constitutional Convention. From this comparison a functional and unified understanding of the "thorough and efficient" standard in the context of modern educational demands can be ascertained. Moreover, absent a compelling argument to the contrary, this unified definition of "thorough and efficient" should apply in each of the states that adopted this standard for education. Finally, the fourth section of this article proposes the adoption of a constitutional amendment in Ohio. The author argues that a constitutional amendment is necessary to effectuate the original intent of Ohio's framers in adopting the standard of "thorough and efficient." Whether other states with the "thorough and efficient" standard should likewise amend their constitutions is beyond the scope of this article. However, themore accurate and precise definition of "thorough and efficient" set forth herein is of value to government officials and education advocates in all the jurisdictions that use "thorough or efficient" in their constitutional standard for education. Depending on their progress in creating a truly "thorough and efficient" education system, advocates in these states might be well advised to pursue a similar constitutional amendment. (Contains 273 footnotes.)