Response process validity evidence can provide researchers with insight into how and why participants interpret items on instruments such as tests and questionnaires. In chemistry education research literature and the social sciences more broadly, response process validity evidence has been used and reported in a variety of ways. This paper's objective is to support researchers in developing purposeful, theory-driven protocols to investigate response processes. We highlight key considerations for researchers who are interested in using cognitive interviews in their research, including the following: the theoretical basis for response process investigations, collection of response process validity evidence through cognitive interviews, and use of that evidence to inform instrument modifications.