The implicit theories teachers hold about the gifted influence their perception of and behavior toward highly able students, thus impacting the latter's educational opportunities. Two persistent stereotypes about the gifted can be distinguished: the harmony hypothesis (gifted students are superior in almost all domains) and the disharmony hypothesis (giftedness implies maladaptive social behavior and emotional problems). The present study investigated whether teachers' implicit personality theories about the gifted are in line with the harmony or the disharmony hypothesis. Using an experimental vignette approach, we examined 321 prospective and practicing teachers' implicit personality theories (based on the big five personality framework) about students described along three dimensions (ability level, gender, and age, resulting in 8 different vignettes), controlling for teachers' age, gender, experience with gifted students, and knowledge about giftedness. Ability level had the strongest effect on teachers' ratings (partial [eta][superscript 2 ]= 0.60). Students described as gifted were perceived as more open to new experiences, more introverted, less emotionally stable, and less agreeable (all ps less than 0.001). No differences were found for conscientiousness. Gender and its interaction with ability level had a small effect (partial [eta][superscript 2]s = 0.04 and 0.03). Thus, teachers' implicit personality theories about the gifted were in line with the disharmony hypothesis. Possible consequences for gifted identification and education are discussed. (Contains 4 tables and 2 footnotes.)