Diagnostic stewardship seeks to improve ordering, collection, performance, and reporting of tests. Test results play an important role in reportable HAIs. The inclusion of HAIs in public reporting and pay for performance programs has highlighted the value of diagnostic stewardship as part of infection prevention initiatives. Inappropriate testing should be discouraged, and approaches that seek to alter testing solely to impact a reportable metric should be avoided. HAI definitions should be further adapted to new testing technologies, with focus on actionable and clinically relevant test results that will improve patient care.