Measurement is a central issue for the self-regulated learning (SRL) field as SRL is a phenomenon difficult to measure in a reliable and valid way. Here, 3 waves in the history of SRL measurement are identified and profiled. Our focus lies on the third and newest one, which combines measurement and intervention within the same tools. The basis for this approach is located in the reactivity principle via students' self-monitoring: when students are aware of their actions, they can react and change what is needed. That happens when the measurement tools promote students' self-monitoring which turn part of the intervention then. Examples of this new approach to SRL measurement and guidelines for implementing it are presented.