The present study aims at investigating student teachers’ attitudes towards heterogeneity, which represent one part of teachers’ profession and determine future teacher action. Particularly, it addresses research gaps regarding the relationship between attitudes and personality traits such as the Big Five, which are also important in the field of teacher professionalism. Through confirmatory factor analysis, the validity of an existing measurement instrument of attitudes was verified in a sample with 294 student teachers. Personality traits represented significant predictors of some of the attitudes measured, but were only able to explain relatively little variance. Practical implications for teacher training are discussed.