Background: Postmastectomy breast reconstruction (PMBR) is an elective, preference-sensitive decision made during a stressful, time-pressured period after a cancer diagnosis. Shared decision making (SDM) can improve decision quality about preference-sensitive choices. Stakeholders' perspectives on ways to support PMBR decision-making were explored. Methods: Forty semi-structured interviews with stakeholders (20 postmastectomy patients, 10 PMBR surgeons, 10 PMBR nurses) were conducted. Clinicians were recruited from diverse practices across the United States. Patients were recruited using purposive sampling with varying PMBR experiences, including no reconstruction. The interview guide was based on an implementation research framework. Themes were identified using grounded theory approach, based on frequency and emotive force conveyed. Results: Engagement in SDM was variable. Some patients wanted more information about PMBR from clinicians, particularly about risks. Some clinicians acknowledged highlighting benefits and downplaying risks. Many patients felt pressured to make a choice by their clinicians. Clinicians who successfully engaged patients through decisions often used outside resources to supplement conversations. Conclusions: Patient-clinician trust was critical to high-quality decisions, and many patients expressed decision regret when they were not engaged in PMBR discussions. Patients often perceived a race- or age-related bias in clinician information sharing. Interventions to support SDM may enhance decision quality and reduce decision regret about PMBR, ultimately improving patient-centered care for women with breast cancer.