atients living with serious illness suffer both physically and psychologically. Although many factors contribute, including disease characteristics, quality of care, social determinants, and systems issues, wide consensus exists that poor communication by health care professionals plays a central role. 1(pp117-219) Physical and psychological suffering worsens when patients do not fully understand their illness, prognosis, and treatment options and when clinicians have not sufficiently elicited patients' values. Consequently, patients may receive medical care inconsistent with their goals. 2 Inadequate communication also leads to higher use of invasive care near death, shorter hospice stays, lower patient quality of life at the end of life, and worse bereavement outcomes for family and caregivers. 3 Poor-quality communication not only affects patients and families but also contributes to clinician burnout, a troubling outcome given current workforce shortages. 4 Although considerable research explores the effect of communication on these outcomes, many questions remain. Setting a clear research agenda would move the field forward. Since the late 1980s, the primary approach to addressing poor communication and unwanted care for patients approaching the end of life has been to promote advance directive completion. Despite legislation encouraging advance directives and numerous dissemination efforts, the outcomes have been disappointing. Initiatives that focus on advance directives alone have changed little in the quality of the experience for seriously patients and families. 1 Many additional aspects of communication that mediate outcomes in serious illness are insufficiently addressed, including emotion, prognostic awareness, goals of care, spirituality and existential issues, and costs of care. 5-8 Furthermore, effective interventions have not been disseminated widely into practice. IMPORTANCE Poor communication by health care professionals contributes to physical and psychological suffering in patients living with serious illness. Patients may not fully understand their illness, prognosis, and treatment options or may not receive medical care consistent with their goals. Despite considerable research exploring the role of communication in this setting, many questions remain, and a clear agenda for communication research is lacking. OBSERVATIONS Through a consensus conference and subsequent activities, we reviewed the state of the science, identified key evidence gaps in understanding the impact of communication on patient outcomes, and created an agenda for future research. We considered 7 broad topics: shared decision making, advance care planning, communication training, measuring communication, communication about prognosis, emotion and serious illness communication, and cultural issues. We identified 5 areas in which further research could substantially move the field forward and help enhance patient care: measurement and methodology, including how to determine communication quality; mechanisms of communicati...