Self-regulated learning (SRL) is of great importance to academic achievement and life-long learning. This study aimed to examine the prediction of three processes of primary students' SRL using students' prior achievement, interest in mathematics, personal best goal orientation, and their perceptions of teachers' feedback one academic year earlier. The SRL processes were planning, monitoring, and adaptive reactions. The sample comprised 2972 (1608 females and 1364 males) primary school students in Hong Kong. Multi-level path analysis determined that prior achievement, interest in mathematics, personal best goal orientation, and feedback predicted students' planning, monitoring, and adaptive reactions after one academic year, with interest and personal best goal orientation being the strongest predictors. Strategies for promoting interest in mathematics and developing personal best goal orientation among primary school students are discussed in the article.