Background: Paramedics are increasingly required to make complex decisions as to whether they should convey a patient to hospital or manage their condition at the scene. Dementia can be a significant barrier to the assessment process. However, to our knowledge no research has specifically examined the process of decision-making by paramedics in relation to people with dementia. This qualitative study was designed to investigate the factors influencing the decision-making process during Emergency Medical Services (EMS) calls to older people with dementia who did not require immediate clinical treatment. Methods: This qualitative study used a combination of observation, interview and document analysis to investigate the factors influencing the decision-making process during EMS calls to older people with dementia. A researcher worked alongside paramedics in the capacity of observer and recruited eligible patients to participate in case studies. Data were collected from observation notes of decision-making during the incident, patient care records and post incident interviews with participants, and analysed thematically. Findings: Four main themes emerged from the data concerning the way that paramedics make conveyance decisions when called to people with dementia: 1) Physical condition; the key factor influencing paramedics' decision-making was the physical condition of the patient. 2) Cognitive capacity; most of the participants preferred not to remove patients with a diagnosis of dementia from surroundings familiar to them, unless they deemed it absolutely essential. 3) Patient circumstances; this included the patient's medical history and the support available to them. 4) Professional influences; participants also drew on other perspectives, such as advice from colleagues or information from the patient's General Practitioner, to inform their decision-making. Conclusion: The preference for avoiding unnecessary conveyance for patients with dementia, combined with difficulties in obtaining an accurate patient medical history and assessment, mean that decision-making can be particularly problematic for paramedics. Further research is needed to find reliable ways of assessing patients and accessing information to support conveyance decisions for EMS calls to people with dementia.