Aim: To evaluate the validity and reliability of the Spanish version of the Self-Assessment Practice Scale for Students (SaPS) in first-year nursing students in Chile. Background: Self-assessment is a process by which students make a judgment about their work and learning process, as well as about their degree of achievement based on pre-established criteria. This process is crucial in learning because it allows students to correct errors and improve their performance. There are no instruments in Spanish specifically designed to measure the self-assessment process in nursing students, so the development and characteristics of this process in this population are unknown. Methods: Cross-sectional study. A translation-back-translation procedure was used. Ten experts evaluated the content validity of the items. After adapting this instrument to the Spanish context, it was applied to 172 university nursing students. The internal structure of this instrument was studied using exploratory factor analysis (EFA) and its reliability was evaluated in terms of Cronbach's alpha coefficients. Results: After expert analysis, the original 20 items included in the instrument were retained. EFA revealed that 3 factors and 17 items were suitable for use with nursing students; the overall reliability of this version of the SaPS was alpha = 0.73. The reliability coefficients for the subscales were: a Seeking external feedback (SEF) alpha= 0.61, seeking internal feedback (SIF) alpha= 0.72; and self-reflection (SR), alpha = 0.75. Conclusions: This study provides evidence to support the validity and reliability of a Spanish version of the SaPS for use with nursing students.