This study examines how various teacher characteristics and contextual factors are related to early primary teachers' beliefs about mathematical teaching and learning and teachers' attitudes toward their own learning of mathematics. A total of 396 early primary teachers across Nebraska participated in the study. Teacher characteristics and contextual factors were grouped into four sets: teacher professional background, teacher mathematical knowledge for teaching, teaching contexts, and students' experiences. Multiple regression analyses were conducted with each set of predictors separately, as well as with all four sets together. The results showed significant relationships between teachers' mathematical knowledge for teaching and teacher-centered beliefs, motivation in learning mathematics, and anxiety toward learning mathematics. Teacher certification level, the number of college math courses taken, and perceived support from colleagues and administrators were also related to some aspects of teachers' mathematical beliefs and attitudes. The findings suggest the potential role of teachers' mathematical knowledge for teaching in improving teachers' mathematical beliefs and attitudes.