Response process validity evidence can provide researchers with insight into how and why participants interpret items on instruments (e.g., tests, questionnaires). In the chemistry education research literature and in the social sciences more broadly, there has been variable use and reporting of response process aspects of studies. This manuscript'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 theoretical basis for response process, collecting response process validity evidence through cognitive interviews, and using that evidence to inform instrument modifications.