Advance care planning (ACP) is an essential part of palliative dementia care and should embrace a collaborative approach involving persons with dementia, family members and various healthcare professionals (HCPs). This study aimed to develop a guidance document for IPC in ACP in dementia care for HCPs from nursing homes, using a mixed-method design and taking an appreciative inquiry approach comprising semi-structured focus groups and interviews with HCPs. The study participants (N=18) included certified nurses, registered nurses, a quality nurse, nurse specialists, team leaders, physicians specialized in old age medicine, psychologists, and a teacher/researcher (mean age 43.8 years; 79% female). The data analysis indicated six elements to include in the guidance document. The first three elements concerned common awareness of collaborative ACP in dementia care, role clarification for various professions, and actively working towards shared goals in collaborative ACP in dementia care. The last three themes focused on the dynamic processes in collaborative ACP in dementia care: interprofessional communication, coordination, monitoring and evaluation. This study provides a guidance document that HCPs could use in practice to identify the elements they can address to improve collaborative ACP in dementia care.