The Student Engagement Instrument is an internationally well-known questionnaire that measures factors related to student engagement. This study analyses the psychometric properties of the "Student Engagement Instrument (SEI)" (Appleton et al., 2006) in a sample of high school adolescents. The scale was administered to 452 high-school students between 13 and 20 years old (M=15.66; DE=1.31) from schools in Concepcion, Chile. Descriptive analysis, internal consistency, temporal reliability, and confirmatory factor analysis were conducted to measure data fitness. The results show good internal consistency and test-retest indices. Results replicated the five and six factors structure reported in international studies.