Evolutionary theory is fundamental to biology, yet evolution instruction in high schools has often been unsatisfactory. How or whether high school biology teachers teach evolution is influenced by their own acceptance or rejection of evolutionary theory, parents' and community members' views, and in the case of some private schools, their religious affiliations. Studies documenting how evolution is taught in public high schools have been conducted, yet private schools remain underresearched. Arkansas high school biology teachers employed by public and private schools were invited to complete a survey composed of the Measure of Acceptance of the Theory of Evolution (MATE) and other items designed to allow comparison of their treatment of topics within evolutionary theory. Specifically, we sought to compare public and private teachers' acceptance of evolution, how they teach it in their classrooms, and how their acceptance of the validity of evolution compares with four other widely accepted scientific theories (cell, gene, germ, and atomic). Results suggest that public school teachers have higher levels of acceptance of evolution than private school teachers. However, teachers in both public and private schools reported lower acceptance of the validity of evolutionary theory compared with the other four scientific theories. Across topics within evolution, natural selection was given the most treatment while human evolution was given the least.