Self-efficacy is the belief in one´s ability to organize and execute the course of action required to produce results under different conditions using the skills one possesses; teachers´ self-efficacy is related to student achievement. This chapter provides an overview of self-efficacy theory related to teachers´ assessment practices within technology education, emphasising the great importance of strengthening teachers´ self-efficacy and collective efficacy as well as assessment literacy regarding their assessment practices in technology education as it affect students´ learning opportunities in school.