The purpose of the study was to examine what scientists studying to become teachers know about the nature of science (NOS) before, during and after a course focused on NOS. The 16 scientists had an average of 9.7 years of work experience. The course was structured to teach knowledge about the aspects of NOS, demonstrate effective methods of teaching NOS, provide examples of successful attempts at meaningfully incorporating NOS into science content, and give students an opportunity to design and teach their own lessons incorporating NOS. Data sources collected include a prepost test of Views of Science and Education, electronic discussion postings, written class assignment of a clinical interview with an adolescent about NOS, video recordings of teaching, and individual interviews conducted three months after the course. Quantitative and qualitative data indicate that the scientists entered the course with much knowledge regarding the tentativeness of science and the nature of observations. There were significant gains in sophistication of view of NOS with regard to the following aspects of NOS: (a) knowing that variety of scientific methods exist, (b) the role of theories and laws, (c) the use of imagination, and (d) the role of subjectivity and objectivity in science.