BACKGROUND: Hypertension control is falling in the US yet efficacious interventions exist. Poor patient reach has limited the ability of pragmatic trials to demonstrate effectiveness. This paper uses quantitative and qualitative data to understand factors influencing reach in Hyperlink 3, a pragmatic hypertension trial testing an efficacious pharmacist-led Telehealth Care intervention in comparison to a physician-led Clinic-based Care intervention. Referrals to both interventions were ordered by physicians. METHODS: A sequential-explanatory mixed methods approach was used to understand barriers and facilitators to reach. Reach was assessed quantitatively using EHR data, defined as the proportion of eligible patients attending intended follow-up hypertension care and qualitatively, via semi-structured interviews with patients who were and were not reached. Quantitative data were analyzed using descriptive and inferential statistics. Qualitative data were analyzed via combined deductive and inductive content analysis. RESULTS: Of those eligible, 27% of Clinic-based (n = 532/1945) and 21% of Telehealth patients (n = 385/1849) were reached. In both arms, the largest drop was between physician-signed orders and patients attending initial intended follow-up care. Qualitative analyses uncovered patient barriers related to motivation, capability, and opportunity to attend follow-up care. CONCLUSIONS: Although the proportion of eligible patients with signed orders was high in both arms, the proportion ultimately reached was lower. Patients described barriers related to the influence of one's own personal beliefs or priorities, decision making processes, logistics, and patient perceptions on physician involvement on reach. Addressing these barriers in the design of pragmatic interventions is critical for future effectiveness. TRIAL REGISTRATION: NCT02996565.