Diagnostic criteria fulfillment is the systematic process of evaluating clinical findings against established diagnostic standards (DSM-5 for psychiatric disorders, ACR/EULAR for rheumatologic conditions, Jones criteria for rheumatic fever, Duke criteria for endocarditis, etc.). Evidence-based criteria typically include major and minor criteria, with specified combinations required for diagnosis. Sensitivity-oriented criteria cast a wider net (fewer missed cases, more false positives); specificity-oriented criteria are more restrictive (fewer false positives, may miss atypical presentations). The NP must understand which criteria apply, how to apply them correctly, and when clinical judgment should override strict criteria adherence (criteria are guides, not absolute rules -- atypical presentations may not meet criteria but still warrant treatment).