PURPOSE Hospitalizations for ambulatory care-sensitive conditions (ACSCs) are seen as potentially avoidable with optimal primary care. Little is known, however, about how primary care physicians rate these hospitalizations and whether and how they could be avoided. This study explores the complex causality of such hospitalizations from the perspective of primary care physicians. METHODSWe conducted semistructured interviews with 12 primary care physicians from 10 primary care clinics in Germany regarding 104 hospitalizations of 81 patients with ACSCs at high risk of rehospitalization. RESULTSParticipating physicians rated 43 (41%) of the 104 hospitalizations to be potentially avoidable. During the interviews the cause of hospitalization fell into 5 principal categories: system related (eg, unavailability of ambulatory services), physician related (eg, suboptimal monitoring), medical (eg, medication side effects), patient related (eg, delayed help-seeking), and social (eg, lack of social support). Subcategories frequently associated with physicians' rating of hospitalizations for ACSCs as potentially avoidable were after-hours absence of the treating physician, failure to use ambulatory services, suboptimal monitoring, patients' fearfulness, cultural background and insufficient language skills of patients, medication errors, medication nonadherence, and overprotective caregivers. Comorbidities and medical emergencies were frequent causes attributed to ACSC-based hospitalizations that were rated as being unavoidable.CONCLUSIONS Primary care physicians rated a significant proportion of hospitalizations for ACSCs to be potentially avoidable. Strategies to avoid these hospitalizations may target after-hours care, optimal use of ambulatory services, intensified monitoring of high-risk patients, and initiatives to improve patients` willingness and ability to seek timely help, as well as patients' medication adherence. Ann Fam Med 2013;363-370. doi:10.1370/afm.1498. INTRODUCTIONR educing the number of avoidable hospitalizations provides opportunities for reducing health care spending and improving both quality of care and quality of life. Avoidable hospitalizations are associated with high and rising costs, and they disrupt elective health care planning and affect patients' daily life. 1 In 1993 Billings et al categorized conditions according to their likelihood of being avoidable through timely and effective ambulatory care, including specialized ambulatory care in many countries such as Germany and the United States.2 Hospitalizations for ambulatory care-sensitive conditions (ACSCs) are potentially avoidable by preventing the onset of disease, controlling an acute episodic illness, or managing a chronic condition effectively.2 Since the 1990s different sets of ACSCs have been described in the United States, United Kingdom, Spain, and other countries with the aim of reducing avoidable hospitalizations by optimal ambulatory-particularly primary-care. R EDUCING HOSPITA L IZ AT IONS F OR A MBUL ATORY C A R E COND...