The prevalence of back pain (BP) among children and adolescents has increased over recent years. Some authors advocate promoting back-health education in the school setting. It is therefore important to adopt a uniform suite of assessment instruments to measure the various constructs. The present study aimed to perform a cultural adaptation of a validated measurement instrument (BackPEI), beginning with a translation and cultural adaptation phase, followed by a second phase to test reliability using a test-retest design. The translation and cross-cultural adaptation were performed based on the guidelines. Reliability was tested by applying the questionnaire to 224 secondary school students, at two different times with a 7-day interval between the tests. In general, the Spanish version presented adequate agreement for questions 1–20, with only question 9 achieving a low Kappa range of .312 [-.152- .189]. The question about pain intensity did not show differences between the averages for the test (4.72 ± 2.33) and re-test (4.58 ± 2.37) (p = .333), and the responses for these two tests were highly correlated (ICC= .951 [.928- .966]; p= .0001). Psychometric testing indicated that the Spanish version of the BackPEI is well-adapted and reliable, based on the test-retest design, providing similar results to the original Brazilian version.