An important goal of The Paris System for Reporting Urinary Cytology (TPS) is to reduce unnecessary atypical diagnoses given to urinary tract cytology (UTC) specimens. Since implementation of TPS at the study institution in 2016, the institutional atypical rate has declined only slightly. The authors speculated that TPS might not have had an immediate impact because several faculty members were involved in TPS committees and because TPS contains elements that already had been integrated into institutional practice. To identify factors contributing to alterations in the institutional atypical rate, the authors examined their practice over the last 22 years.