Teachers play a key role in the development of self-regulated learning (SRL), especially in primary education. However, current results indicate that teachers are either inadequately or only moderately fulfilling this key function, as they spend little time in the instruction of SRL strategies. The objective of the current study was, therefore, to develop an intervention that guides teachers to provide students with SRL strategies and investigate if additional teacher training (ATT) can enhance the intervention effects. Data of 607 fourth-graders were used to analyze their SRL within a pretest/posttest control-group design using a questionnaire and a learning diary. Contrasting the data of the groups actively participating in the intervention (simple intervention group and trained-teachers intervention group) with the data of a passive control group revealed positive effects of the intervention in terms of an increase in their reported use of SRL strategies (questionnaire and diary data). However, we found no transfer effects on achievement, as well as that the ATT had no beneficial effect on results at the student level. For fourth-graders, the developed intervention seems appropriate to impart SRL strategies to them. For teachers, it represents a potential opportunity to instruct SRL strategies to their students in their classes.