To enhance students' understanding of nature of science (NOS), teachers need adequate pedagogical content knowledge related to NOS. The educational design research study presented here describes the design and development of a pre-service chemistry teacher education course on NOS instruction. The study documents two iterative cycles of problem analysis, design, implementation, and evaluation. The main aims of the study were (1) to create an in-depth and detailed description of the process used in the development of the course and the design solutions produced, and (2) to evaluate how the design solutions affected participants' commitment to teach NOS. Based on the problem analysis based on challenges recognized from the previous research, three design solutions were produced: (1) definition of central dimensions of domain-specific NOS for chemistry education, (2) teaching cycle for explicit and structured opportunities for reflection and discussion, and (3) design assignments to translate NOS understanding into classroom practice. The major data-sources used in the evaluation of the design solutions were the four in-depth interviews conducted after the course. Based on the evaluation, the design solutions supported internalizing understanding of NOS and transforming the understanding to instruction. Supporting the implementation of new innovative teaching practices such as NOS instruction in pre-service teacher education is a challenge. However, the success of the participants in implementing NOS instruction demonstrates, that a pre-service teacher education course can be successful in producing early adopters of NOS instruction and thus might be one of the first steps in injecting NOS instruction into the curriculum.