The goal of the present study was to examine preschool teachers' attitudes, beliefs, and emotional reactions in response to vignettes depicting a range of children's peer group behaviors. Participants were N = 405 female preschool teachers, aged 20-65 years (M = 41.54, SD = 10.50), recruited from childcare centers and preschools located primarily in Ontario, Canada. Participants read a series of short scenarios depicting hypothetical children engaging in a range of peer-group behaviors at preschool, including: (1) physical aggression; (2) relational aggression; (3) shyness; (4) unsociability; (5) rough-and-tumble play; and (6) exuberance. Following each vignette, teachers responded to a series of items assessing their attitudes (e.g., intent to intervene, tolerance), beliefs (e.g., implications for children's social and academic functioning), and emotional reactions (e.g., anger, worry) toward each child behavior. Results indicated that preschool teachers expressed more negative views in response to child aggression as compared to social withdrawal. Exuberance and rough-and-tumble play elicited comparatively positive, but also somewhat mixed responses. However, clear differences were also evidenced among sub-types of both aggression and social withdrawal. Findings are discussed in terms of the implications of teachers' distinctions among different types of young children's peer-group behaviors at preschool. (author abstract)