Despite considerable focus on evolution knowledge–belief relationships, little research has targeted populations with strong content backgrounds, such as undergraduate degrees in biology. This study (1) measured precertified biology and non-biology teachers' (n = 167) knowledge of evolution and the nature of science; (2) quantified teacher preferences for the teaching of creationism in schools; (3) examined the associations among knowledge and belief variables; and (4) contrasted the knowledge and beliefs of prospective biology teachers with those of non-biology teachers. Methodologically, teacher knowledge was quantified by using three measures and studied in relation to certification area, self-reported religiosity, personal conflict concerning science and religion, and completion of an evolution course. We found (1) generally low levels of knowledge of evolution and the nature of science—and high misconception magnitudes—in both biology and non-biology teachers; (2) comparable antievolutionary positions in biology and non-biology teachers: nearly half of the teachers in both groups advocated for the inclusion of creationism in school; (3) weak association between knowledge and preference/belief variables; and (4) no difference in preference for teaching creationism between those teachers who had taken an evolution course and those who had not. Overall, biology and non-biology teachers were found to display “mixed” and “novice naturalistic” evolutionary reasoning patterns. © 2009 Wiley Periodicals, Inc. Sci Ed93:1122–1146, 2009