Purpose <p>Up to 30% of patients with hormone receptor-positive (HR +) breast cancer do not start adjuvant endocrine therapy (AET) as prescribed. AET non-initiation is associated with increased recurrence and decreased survival. We conducted a single-arm, open-pilot study to assess the feasibility and acceptability of a nurse-led, culturally sensitive intervention (‘INITIATE’) to optimize AET initiation.</p> Methods <p>From 9/2022 to 8/2024, we recruited 35 patients with stage I-IIIB, HR + breast cancer who delayed or reported hesitancy to start AET. INITIATE included two virtual sessions delivered in English or Spanish with an oncology nurse. Feasibility was defined by enrollment rates (&gt; 50% eligible patients), intervention attendance (≥ 70% of patients attending one of two sessions), and retention (&gt; 70% completing the 3-month questionnaire). At baseline, 1&#xa0;month, and 3&#xa0;months post-baseline, patients self-reported sociodemographics, AET initiation, intervention acceptability (Client Satisfaction Questionnaire-3), and other psychosocial outcomes. We conducted semi-structured, qualitative exit interviews to gather additional feedback. We computed descriptive statistics for the quantitative outcomes and conducted a rapid qualitative analysis of the interview data.</p> Results <p>We enrolled 45.5% (35/77) of eligible patients; 82.9% (29/35) attended at least one intervention session, and 77.1% (27/35) completed the 3-month assessment. Most patients (68.6%) were White, and 37.1% identified as a racial or ethnic minority. Qualitatively, patients reported that INITIATE helped them understand the importance of taking AET and improved their coping skills. Ninety-six percent reported high acceptability, and 88.9% started their AET by three months post-baseline.</p> Conclusion <p>INITIATE is mostly feasible and acceptable and demonstrates promise for promoting AET initiation among patients with HR + breast cancer.</p>