Introduction: In 2010, national guidelines recommended that women with nonmetastatic, hormone receptor-positive breast cancer take adjuvant hormone therapy for 5 years. As results from randomized clinical trials became available, guidelines were revised in 2014 to recommend 10 years of therapy. Despite evidence of its efficacy, low initiation rates have been documented among women insured by New York State Medicaid. This article describes a coordinated quality improvement pilot conducted by a state department of health and Medicaid managed care plans to engage women in guideline-concordant adjuvant hormone therapy., Methods: Women enrolled in Medicaid managed care with nonmetastatic, hormone receptor-positive breast cancer and who had surgery from May 1, 2012, through November 30, 2012, were identified using linked Medicaid and Cancer Registry data. Adjuvant hormone therapy status was determined from Medicaid pharmacy data. Contact information for nonadherent women was supplied to health plan care managers who conducted outreach activities. Adjuvant hormone therapy status in the 6 months following outreach was evaluated., Results: In the 6 months postoutreach, 61% of women in the contacted group filled at least 1 prescription, compared with 52% in the noncontacted group. Among those with at least 1 filled prescription, 50% of the contacted group were adherent, compared with 25% in the noncontacted group., Conclusion: This pilot suggests outreach conducted by health plan care managers, facilitated by linked Medicaid and Cancer Registry data, is an effective method to improve adjuvant hormone therapy initiation and adherence rates in Medicaid managed care-insured women.