Achievement in a course mostly depends on the students' characteristics and how teachers make their courses effective for their students' learning. Although different characteristics of teachers and students can affect learning outcomes, new approaches like STEM may cause new characteristics which affect students' achievement as STEM attitudes. This study examines the correlation between secondary school students' STEM attitudes and their achievement in the Technology and Design Course (T&DC). A correlational survey model was applied in the study. A total of 400 students studying in the seventh and eighth grades constitute the sample of the study. A personal data form and STEM attitude test were utilized to collect data. Pearson Correlation Analysis and Regression Analysis techniques were used in the data analysis process. As a result of the analysis, it was found a positive and significant correlation between students' Technology and Design Course achievement and STEM attitudes. Students' attitudes to STEM predict their achievement in the Technology and Design Course by 5.1%. Students developing positive STEM attitudes can further enhance achievement in the (T&DC), which enables students to acquire the necessary design skills to produce technology in the future.