Unfortunately, for the most part, teachers do not teach the Nature of Science (NOS). Even when teachers have adequate NOS knowledge, their knowledge still does not make its way into practice. While there are various reasons for this happening, this study has isolated other, more typical, constraints to teaching in order to look more closely at the influence of personal epistemological beliefs, understandings of NOS, and their effects on practice. In an effort to minimize typical constraints of time for the teaching of NOS, a sixth grade physical science course was chosen as a way to minimize this constraint. Within this course there was a School District- mandated schedule for the teaching of NOS. This curriculum map included details of what NOS topics to teach and when to teach them. In Phase One of the study, correlational relationships between these understandings of NOS and personal epistemological beliefs were investigated. A Pearson Correlation Coefficient of 0.62 was calculated based on 28 sixth grade science teachers. In Phase Two of the research, eleven participants were chosen for a more in-depth analysis. Through the use of triangulation of interview data, classroom observations, artifact collection and survey scores to ascertain the constraints for each individual, even though few constraints could be verified that would affect instruction, only three of eleven participants taught NOS. Personal epistemological beliefs play a role in the way instruction is approached in either a constructivist or non-constructivist manner.