Technical work differs significantly from most other forms of work. This chapter explores those differences and how the differences pose important challenges for ethnographers who seek to study engineers, scientists, and other technical workers. The chapter summarizes the experience of thirty-five years’ of studying technical work to capture the social dynamics of technical worlds in the way that an earlier generation of scholars captured the social worlds of industrial, craft, and clerical work. The discussion revolves around how to handle six fears that ethnographers face when studying technical work: the fear of looking stupid, the fear of mishearing, the fear of failing to understand what technical terms mean, the fear of not capturing the complexity of the work, the fear of not finishing the study, and the fear of not being able to make sense of one’s data.