The aim of this study was to investigate whether an epistemological adequacy (knowledge of the Nature of Science, NOS) contributes to a better understanding and the acceptance of the Theory of Evolution by Natural Selection (ThENS). It was performed in two parts with the help of two questionnaires: 1. with students of Education, with a minimum familiarity to ThENS and NOS, before and after the application of a general biology course, and 2. with 200 Science Education teachers of various specialties who teach or have taught biology-related subjects. The education students showed some moderate levels of proficiency regarding NOS that was improved statistically significantly, even after a limited teaching intervention. An interesting founding was that, while their understanding of the ThENS was not very much improved by the course, it was found a positive correlation between their NOS familiarity and acceptance of evolution. As for the Science teachers, besides the above queries, some other variables were additionally investigated: E.g. to what extent, a better Epistemological Adequacy (knowledge of the Nature of Science) can influence their understanding and acceptance of the ThENS, or whether this affiliation could have been affected by their college or university instruction. The results showed a positive correlation between their epistemological adequacy and the acceptance and understanding of ThENS.