The Perceptions of Inclusion Questionnaire (PIQ) assesses the perceptions of inclusion in 3rd to 9th grade students through three scales: social inclusion, emotional inclusion, and academic self-concept. This study aimed to establish the psychometric properties of the Spanish version of the instrument (PIQ-Spa) since no prior formal validation of the PIQ-Spa has been conducted. One thousand Spanish adolescents (12 to 16 years, M = 14, SD = 1.41) participated. The analytical process involved four phases. The initial phase employed confirmatory factor analysis to compare one-factor and three-factor models. Subsequent phases assessed the reliability, convergent, and discriminant validity of the instrument. The model with three correlated factors obtained the best indices of overall fit. Convergent validity was supported by significant factor loadings and average extracted variances (AVE) exceeding 0.5 for all factors. Discriminant validity was supported by confidence interval tests, HTMT ratios, and average extracted variances exceeding the squared correlations between factor pairs. These findings offer robust support for the PIQ-Spa's validity and reliability in assessing Spanish adolescents' perceptions of inclusion. Within the Spanish educational landscape, the PIQ-Spa can equip educators with a deeper understanding of student perceptions, enabling them to identify areas for improvement in fostering inclusive school environments.