Self-regulation of learning (SRL) processes are positively linked to academic performance, school engagement, and success. Although its importance is recognized, the research problem emerges from the limited evidence of a measurement instrument for secondary school students. It is necessary to design instruments for measuring this variable in the Latin American educational context. Having a valid and feasible instrument for its application, which measures the three phases of the SRL process (disposition, performance, and evaluation), will allow identifying those variables that are at an inadequate level of development in secondary school students. In addition, it would allow knowledge of how the processes of self-regulation and learning strategies are articulated with academic performance, facilitating progress towards new strategies or programs for the improvement of the complex processes of SRL at this educational level. The aim of this study was to design, validate and analyze the feasibility of applying a self-regulation of learning instrument for secondary school students in Chile. The method consisted of an instrumental design, and international guidelines for the construction of scales were considered. The design implemented three stages: the first consisted of a systematic literature review to identify existing scales on SRL, the second consisted of the content validation of the instrument involving the evaluation of expert judges, and finally, the third stage consisted of the evaluation of the instrument's feasibility by conducting cognitive interviews with students and a pilot application of the instrument. The results showed an agreement of judges in relation to the items and dimensions of the instrument, in addition to meeting the feasibility criteria for its application. The original questionnaire had 74 items, but after the different validation stages of this study it was comprised by a total of 70 items distributed in 12 dimensions: (1) Planning for self-observation of study behavior; (2) Organization of environmental and material resources; (3) Self-efficacy beliefs for planning and organization of study; (4) Monitoring of study behavior; (5) Monitoring of learning; (6) Cognitive strategies; (7) Help-seeking; (8) Self -assessment of study behavior; (9) Self-assessment of learning; (10) Adaptation/regulation; (11) Causal attributions of failure to external factors; (12) Causal attributions of failure to effort/skill. It is concluded that the instrument is valid by expert judges and feasible to measure SRL in students of Secondary Education in Chile, being a useful resource for the measurement of cognitive-motivational variables related to study success and permanence in the educational system. In addition, this study is considered a contribution in methodological aspects, since the design process of the instrument is described in its different stages and allows the guiding of other studies that propose to design and validate scales, since it shows the steps followed, based on international guidelines, and specialized literature of test construction and validation, becoming a practical example of how to conduct these psychometric procedures.