The study aimed to translate, culturally adapt and validate the Spanish version of the "Assessing Reasons for School Non-attendance" (ARSNA) originally developed by Havik, Bru and Ertesvåg in 2015 to assess the reasons for school absence in adolescents. We used the back-translation method to translate and adapt the instrument without substantially altering it. A total of 1168 Spanish adolescents (M = 15.03, SD = 2.40) enrolled in 6 secondary education institutes participated in the study. The confirmatory factor analysis establishes a four-dimensional model (FI: Somatic symptoms; FII: Subjective health complaints; FIII: Unjustified absences; FIV: School refusal) with 16 items and invariant depending on gender. The results obtained provide the Spanish version of the ARSNA with good understandability, internal consistency, and reliability for measuring the causes of lack of school attendance. This research makes a new instrument available to the Spanish population that evaluates reasons for school absenteeism.