In the province of Quebec, Canada, a trend towards full inclusion has impelled teachers to adapt their instruction to meet the needs of both advanced and weaker learners in regular school settings. The main purpose of the present investigation was to develop and validate the Differentiated Instruction Scale (DIS), which assesses the use of instructional adaptations and academic progress monitoring strategies in general education classrooms. A total of 125 elementary school teachers participated in a cross-sectional study, allowing us to develop and validate the DIS. Overall our results show that the DIS is composed of two factors that are consistent with the predicted constructs (instructional adaptations and academic progress monitoring). Evidence of convergent validity is provided through correlations among DIS' subscales and two criteria: (1) teachers' autonomy support and (2) perceptions of school climate. Results also reveal that teachers tend to use instructional adaptations that do not require much preparation or tailored instruction. The DIS could thus be used in future research to investigate outcomes of differentiated instruction. Moreover, it could provide useful information on optimal strategies for promoting learning in children with different abilities in general education classrooms.