Although there are an increasing number of studies on assessing teacher emotions in mainstream education, there is a lack of appropriate measurement tools to evaluate the emotions of teaching assistants (TAs) who need to take care of students with a range of special educational needs (SEN). This study tested the generalizability of the 24-item teacher emotion inventory (TEI), among 204 TAs from 122 secondary schools with inclusive education in Hong Kong. We conducted both confirmatory factor analysis (CFA) and Rasch analysis to test the within-network validity of the TEI. For the between-network validity, we examined the relationships between TAs’ emotions and their attitude toward inclusive education. The Rasch analysis supported the scale’s dimensionality and item fit statistics. The CFA supported the five-factor solution of the TEI. The results also showed statistically significant correlations between positive emotions (joy and love) and TAs’ attitudes toward inclusive education. TAs’ negative emotions (anxiety, anger, and stress) appeared to be negatively correlated with their attitude toward inclusive education. The results supported that TEI is a useful tool to assess the emotions of TAs that play a pivotal role in assisting both school teachers and SEN students, who are more likely to face increased emotional challenges than those not needing to educate SEN students. Implications of this study to enrich the current scope of research on understanding teacher emotions across educational levels and settings are discussed. Copyright © 2022 Yang, Hsu, Ye and Sin.