This article discusses the key decisions and steps that have partially formalized instruction in the responsible conduct of research (RCR) in U.S. research institutions, the different purposes for offering and/or requiring such instruction, and suggestions for what needs to be done to enhance the professional development of researchers in the future. RCR education has developed during three distinct eras: the 1980s, when policy makers were most concerned with defining and investigating research misconduct; the 1990s, when there was significant but highly decentralized growth in RCR instruction; and the years since 2000, when there have been a series of reforms and educational developments. There is still a need for scientists, universities, and professional societies to develop consensus on best ethical practices in many areas of scientific research. More also needs to be learned about assessing the quality of RCR instruction and the effects of training on researchers' behavior. To help set the course for RCR instruction in the future, more effort and funding need to be directed to studying actual research behavior and the factors that influence it; RCR educators and administrators must develop a common vocabulary and framework for developing and evaluating the impact of RCR instruction; and research institutions and funding agencies alike need to take a more active role in promoting and supporting RCR instruction.