Method sections in psychology articles differ in the amount of information they provide, or the level of specificity at which they do so. This can make incremental research (e.g., replication efforts) difficult, because potentially relevant methodological decisions or practices may not be reported. As yet, these unwritten practices have not been systematically studied; the current work represents a first attempt in this direction. For this paper, we interviewed 22 experimental psychologists in the Netherlands to find out about these unwritten aspects of experimenting, as well as their opinions and beliefs regarding these practices. Thematic analysis of the transcripts suggests that (a) experimental psychologists indeed employ a variety of methods that they consider relevant yet do not routinely report in method sections, and (b) these unwritten practices seem to fall into two broad categories: ‘professionalism’ and ‘the production of good data’. We discuss implications for psychological research generally, and the replication debate more specifically.