Researchers in psychiatry are increasingly moving away from disorder-based distinctions and toward dimensional and transdiagnostic definitions of mental health, citing rising concerns about the validity of categorical definitions and the diminishing utility of case-control designs. These frameworks seek to map normal variation of mental health in the general population that does not obey traditional diagnostic boundaries and prescribes no clear division between individuals with mental illness and healthy individuals. While there is great enthusiasm for this initiative, questions abound. What constitutes a transdiagnostic study? How can we advance knowledge without a standardized rubric for defining clinical phenomena consistently across studies?