This study aimed to understand the role of load reduction instruction (LRI), a framework of instructional strategies designed to reduce cognitive load, and its association with motivation, engagement, and learning outcomes in mathematics. We examined data from 221 students from 39 classrooms and tested a hypothesised longitudinal multilevel model. The results indicated positive associations of LRI with gains in motivation, engagement, and achievement. These effects were evident at both student- and classroom-levels, after accounting for prior variance, and after accounting for age, gender, and socioeconomic status at the student level. The findings are discussed in light of the importance of considering motivation and engagement as vital educational outcomes alongside achievement, as well as the role of cognitive load reduction strategies--including those associated with explicit instruction and independent enquiry--in optimising these outcomes.