Recent science education standards emphasize the importance of the instruction of nature of science (NOS) concepts at all levels of schooling from pre-K to K-12. Delivering a proper NOS education to students is excessively dependent on their teachers with an adequate understanding of NOS concepts. The present study investigated the science conceptions of preschool and elementary teacher candidates. The data collected from a total of 506 prospective teachers were analyzed with respect to the following demographic variables: majors, genders, grade levels, high schools, and GPAs of teacher candidates. "Student Understanding of Science and Scientific Inquiry (SUSSI)" developed originally by Liang et al. (2008) was the instrument used to collect data in this study. The data analyses were conducted using MANOVA and Pearson Correlation Coefficient. The corresponding mean scores of the teacher candidates in specific aspects of NOS ranged from "poor" to "informed" conceptions of science. All but one of the demographic variables yielded statistically insignificant results on the NOS conceptions of teacher candidates. The majors of the teacher candidates were detected as a significant variable influencing the conceptions of the teacher candidates. The results of the study were discussed in reference with the relevant literature.