High self-efficacy is a marker of successful teaching and is, therefore, a subject of great interest to research on inclusive education. One of the most frequently used instruments to assess such beliefs is the Teacher Efficacy for Inclusive Practice (TEIP) scale. Although used widely, some studies did not precisely replicate the original factor structure, and no short form of the TEIP scale currently exists, although this could enhance measurement efficiency. This study: (1) systematically assessed the TEIP scale's factor structure and psychometric properties; (2) identified potentially problematic items and developed a more concise short form of the scale; and (3) evaluated its dimensionality and criterion and convergent validities using three validation samples of teachers in three different countries (486 in Switzerland, 189 in Australia and 276 in Canada). Compared to the full-length TEIP scale, the TEIP-SF uses half the items, demonstrates better model fit and reveals a clearer distinction of domain-specific factors. In conclusion, the TEIP-SF represents a concise, efficient means of assessing teachers' self-efficacy about teaching in inclusive classrooms.