Implementation of population-based colorectal cancer screening programs by Medicaid health plans could address colorectal cancer screening disparities. Our objective is to identify facilitators and barriers to implementation of a population-based colorectal cancer screening program by Washington State Medicaid health plans. We conducted semi-structured interviews with leadership from 2 statewide and 3 national Medicaid plans. We organized the interview questions around the Consolidated Framework for Implementation Research (CFIR). We analyzed interview transcripts, guided by directed content analysis, and identified facilitators and barriers to Medicaid health plan implementation of population-based colorectal cancer screening programs. Robust health plan (inner setting) quality improvement infrastructures were facilitators. Lack of statewide Medicaid policy incentives (external setting) to increase colorectal cancer screening were barriers to potential implementation. Efforts to address identified barriers through local and national policies and statewide data sharing efforts may support Medicaid health plan implementation of population-based colorectal cancer screening programs.