To provide context surrounding the history of single-case research and to act as a benchmark for which future changes across the fields and disciplines that use single-case methods may be compared, we conducted this study to serve as an update and extension on the trends and prevalence of single-case research in the peer-reviewed literature. Our analytical sample was derived from 20 peer-reviewed journals over a 40-year timespan. Results indicate that since 1978, approximately one in six publications within our examined body of research employed a single-case research design. Exploratory moderator analyses revealed that a journal's focus on behavior analytic research, and a journal's impact factor moderated the prevalence of single-case publications within a journal. We discuss our findings in relation to prior studies examining the prevalence and trends of single-case research and future directions for single-case researchers to improve the quality, value, and understanding of single-case methodology (https://osf.io/fns3m/).