This study aims to evaluate the implementation of differentiated instruction in Chemistry classes for Grade X in senior high schools in Gorontalo City using the Countenance Stake evaluation model. This model was selected for its ability to provide a comprehensive overview through the analysis of antecedents, transactions, and outcomes, enabling an in-depth understanding of the quality of instructional planning, the execution process, and the learning outcomes achieved. A qualitative approach with a case study method was employed, involving teachers, students, and school principals as key informants. Data collection techniques included in-depth interviews, observations, and document analysis. The findings indicate that, in the antecedent aspect, most teachers had developed instructional materials aligned with the principles of differentiated learning, although limitations were still observed in the use of digital learning media. In the transaction aspect, the implementation of differentiation strategies was generally effective, particularly in content and process differentiation; however, product differentiation requires further strengthening. As for the outcomes, differentiated instruction positively contributed to improved student learning outcomes and motivation, although significant variations in results were observed across classes. The study recommends enhancing teacher training, optimizing learning resources, and strengthening collaboration among educators to ensure the sustainability and effectiveness of differentiated instruction. Keywords: Evaluation, Differentiated Instruction, Chemistry, Senior High School, Countenance Stake Model.