Advance care planning is important to promoting and communicating one's preferences, values and interests when one lacks capacity to make health care decisions, including those towards the end of life. A comparison of advance care planning between the USA and the UK reveals similarities and differences in policy, implementation and the social work role. The USA has a longer history of advance care planning and one that is oriented towards the general public, regardless of health status. The UK is newer to advance care planning and focuses its attention on the patient population, especially people with life-limiting illnesses. Who is meant to initiate advance care planning also differs between the USA and UK. The USA and UK have different legal and informal documents related to advance care planning, with variations and inconsistencies within the USA and UK as well. As the key member of the hospice and palliative care team concerned with psychosocial care, social workers can assume vital roles, including patient and family education; promoting meaningful communication among patients, family members and health care providers; assisting people facing illness in documenting their preferences; and advocating for patients' wishes. As strong advocates, communicators and counsellors, social workers can be leaders in encouraging and facilitating advance care planning.