Background: Teachers' level of knowledge regarding autism and their attitudes towards inclusion are major levers for the successful schooling of autistic students. However, there are currently insufficient validated tools for evaluating these two concepts among teachers that are adapted to the French context and to the constraints of the classroom setting. Aims: This study was designed to test both the validity of The Autism Knowledge Screening Scale (AKSS) and of the Autism Attitude Scale for Teachers (AAST) among French teachers. Sample: Our final sample consisted of 307 French teachers (50.5% primary school teachers and 49.5% secondary school teachers). Methods: First, confirmatory factor analyses were conducted to test the two initial factor structures and an exploratory factor analysis was conducted regarding the AKSS. Second, criterion validity was assessed for each of the two scales. Results: Concerning knowledge of autism, a two-factor model (8 items) explaining 53% of the variance was observed. The first factor represented knowledge about aetiology and the second represented knowledge about symptoms. Concerning attitudes towards autism, a one-factor model (14 items) exhibited good model fit (X [superscript 2]/df = 1.71, RMSEA = 0.048, AGFI = 0.979, SRMR = 0.068, CFI = 0.987, NNFI = 0.984). As expected, participants who were specialized teachers, had training, and a high degree of contact with autism had more knowledge (regarding aetiology but not regarding symptoms) and more positive attitudes. Conclusions This study validated two quick-to-use tools for making an initial diagnosis of teachers' knowledge and attitudes regarding the school inclusion of autistic children. The use of these tools could help to fine-tune the content of training programs for teachers and test their efficacy, particularly in France where the inclusion of autistic children is still far from international standards.