Objectives: The CF Foundation sponsored competitive awards for Mental Health Coordinators (MHCs) from 2016-2018 to implement the international guidelines for mental health screening and treatment in US CF centers. Longitudinal surveys evaluated success in implementing these guidelines using the Consolidated Framework for Implementation Research (CFIR). Methods: MHCs completed annual surveys assessing implementation from Preparation/Basic Implementation (e.g., using recommended screeners) to Full Implementation/Sustainability (e.g., providing evidence-based treatments). Points were assigned to questions through consensus, with higher scores assigned to more complex tasks. Linear regression and mixed effects models were used to: 1) examine differences in centers and MHC characteristics, 2) identify predictors of success, 3) model the longitudinal trajectory of implementation scores. Results: 122 MHCs (88.4% responded): Cohort 1 N=80, Cohort 2 N=30, Cohort 3 N=12. No differences in center characteristics were found. Significant improvements in implementation were observed across centers over time. Years of experience on a CF team was the only significant predictor of success; those with 1-5 years or longer reported the highest implementation scores. Change over time was predicted by >5 years of experience. Conclusions: Implementation of the mental health guidelines was highly successful over time. Funding for MHCs with dedicated time was critical. Longitudinal modeling indicated that CF centers with diverse characteristics could implement them, supported by evidence from the CF Patient Registry showing nearly universal uptake of mental health screening in the US. Years of experience predicted better implementation, suggesting that education and training of MHCs and retention of experienced providers are critical to success.