The purpose of this case study is to delve into the complexities of the early development of preservice chemistry teachers' science teaching orientations, knowledge of learners, knowledge of instructional strategies, and knowledge of assessment during a two-semester intervention designed to enhance their pedagogical content knowledge (PCK) for teaching nature of science (NOS). Thirty preservice chemistry teachers enrolled in a Research in Science Education course participated in the study. Qualitative data sources included responses to an open-ended instrument, interviews, observations, and artifacts such as lesson plans and reflection papers. Through the in-depth analysis of explicit PCK and constant comparative method of analysis, we identified the influence of the intervention on participants' PCK for NOS. Analysis of data revealed four major themes related to the nature of preservice chemistry teachers' NOS teaching practices and their PCK for NOS: (1) prerequisite knowledge and beliefs are necessary to teach NOS, (2) there is a developmental progression of PCK for NOS from knowledge to application level, (3) teachers need some comfort in their NOS understanding to teach NOS, and (4) the higher integration of PCK components leads to successful NOS teaching practices. Implications for science teacher education and research are discussed.