The aim of this study was to analyze the psychometric evidence of scores on the School Anxiety Inventory (SAI). The SAI was administered to a sample of 520 secondary education students, aged from 12 to 18 years. Exploratory and confirmatory factor analyses supported the correlated four-factor structure related to school situations (Anxiety about Academic Failure and Punishment, Anxiety about Aggression, Anxiety about Social Evaluation, and Anxiety about Academic Evaluation) and the three-factor structure related to the response systems of anxiety (Cognitive Anxiety, Psychophysiological Anxiety, and Behavioral Anxiety). Internal consistency and test-retest reliability were appropriate. The results also revealed positive and statistically significant correlations between the SAI and the State-Trait Anxiety Inventory (STAI).