This article describes the development and validation of the School Achievement Motivation Rating Scale (SAMRS). A group of 30 teachers participated in the construction and selection of behavioral characteristics related to achievement motivation in school situatiops based on the literature in the field. A total of 2,063 elementary and secondary students participated in this study. Evidence showed that the SAMRS scores were internally consistent and stable. High correlations were found between the SAMRS scores and grades or grade point averages, and moderate correlations were found between scores of the SAMRS and those of standardized tests. Evidence of concurrent and construct validity was established through correlating the SAMRS scores with scores on a number of measures including scales measuring need for achievement, locus of control, self-esteem, and anxiety as well as two measures of peer observation.