Introduction: The educational inclusion of students with Autism Spectrum Disorder (ASD) in Spain has been promoted through regulations such as LOMCE and LOMLOE. However, its effective implementation depends on teachers’ attitudes and perceptions. This study analyzes teachers’ feelings, attitudes, and concerns regarding the inclusion of students with ASD. Methods: A quantitative, descriptive, and cross-sectional study was conducted with a sample of 2310 teachers from different educational stages in Spain. The SACIE-R and INTEA questionnaires were used to assess teachers’ perceptions of inclusion. ANOVA tests and Spearman correlations were applied for statistical analysis. Results: The results show that the variable “Attitudes” follows a normal distribution, indicating a stable perception of inclusion. In contrast, the variables “Feelings” and “Concerns” present an inverse relationship: the greater the concern, the fewer positive feelings toward inclusion. Significant differences were found based on gender, type of school, educational stage, and teaching specialty. Discussion: Positive attitudes toward inclusion are associated with greater training and specialization in diversity. Special Education teachers show better perceptions, while in Secondary Education, concerns and negative feelings prevail. Continuous training emerges as a key factor in improving teachers’ perceptions. Conclusions: The study highlights the importance of training programs and support strategies to promote effective inclusion. Strengthening support networks and teacher training is recommended to improve attitudes toward the inclusion of students with ASD.

Inclusive education aims to ensure equitable access to quality education for all students, including those with Autism Spectrum Disorder (ASD). This research analyzes the attitudes and competences of non-university Spanish teachers regarding the inclusion of students with ASD, considering relevant variables in previous studies such as teacher training, prior experience, and educational context, among others. The study involved a sample of 2310 teachers in active service during the 2023–2024 school year. Data collection was conducted through two questionnaires: the INTEA-EDG questionnaire, designed to measure teachers’ beliefs and attitudes towards the inclusion of students with ASD, and the CEFI-R questionnaire, which evaluates teachers’ competencies and skills for inclusive education. The results reflect a generally positive attitude towards the inclusion of students with ASD in mainstream schools, although significant variations were found depending on variables such as previous experience, teaching specialization, and specific training received. Based on these and other findings, the study highlights the need to strengthen initial and continuous training in inclusive education and attention to diversity of students with ASD, promote early positive contact with students with ASD, and foster collaborative work and the design of inclusive learning environments.