Purpose: The purpose of this study was to examine the role of teacher characteristics and school demographics in teachers' perceptions of children's cognitive abilities. Most researchers find that teachers' personal characteristics are not related to their perceptions of their children's cognitive abilities. In a 2011 study, Douglas Ready and David Wright find that socioeconomic characteristics of the classroom and the school have a stronger relationship to teacher biases than the personal characteristics of the teachers themselves. While they use a nationally representative sample, Ready and Wright purposely look only at kindergarten teachers. Because there are so few male kindergarten teachers, Ready and Wright ignore gender as a variable. This study used a national database to examine the role of teacher characteristics, including gender, and school demographics in teacher perception in all grades. Method: This study used the National Education Association's KEYS database to examine the relationship between teacher perception and student achievement. This database consists of results from self-administered surveys of school staff and parents that are used to identify areas where schools can improve teaching and learning. Some 1,800 schools have participated in the KEYS data initiative. This study compared data on teacher perceptions of the abilities of their classrooms with school-wide standardized testing results using one-way, two-way, and factorial ANOVA as well as univariate analysis to examine five research questions. These five questions focused on the accuracy of teachers' perceptions of their students' abilities and how that accuracy varied across the race of the student, the grade level of the student, the characteristics of the teachers, and the socio-demographic characteristics of the school and its neighborhood. Findings: Teachers, on average, are quite accurate in their perceptions of their students' cognitive abilities. However, that average accuracy hides wide disparities among different groups of teachers. The socioeconomic (SES) status of the parents of the students served by the school and the type of community it is located in had a strong relationship with the accuracy of teacher perceptions. Schools with lower-income students and schools located in more urban communities tended to overestimate student ability while schools with upper-middle income students and those located in small towns tended to underestimate student ability on average. Teachers systematically perceived minority students to have greater cognitive ability than their standardized test score results would suggest while systematically underrating white students relative to their standardized test score results. Middle school and high school teachers were more likely to overestimate student cognitive ability than their elementary counterparts. Teachers at all levels overestimated minority students' cognitive abilities relative to their estimates of white students' abilities. Teacher personal characteristics were not significant predictors of teacher accuracy in their perceptions of students. The SES of the parents of the children served by the school and the location of the school's neighborhood were significant predictors. This suggested that it is environmental characteristics of the school, rather than individual teacher characteristics that had the most influence on teacher perception of student cognitive ability. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]