Informal caregivers are those who provide unpaid care to a relative or friend with a chronic illness, disability or other long-lasting health or care need. Providing informal care in the context of chronic health conditions presents a significant global challenge. Examination of the determinants of informal caregivers’ behaviour, especially in terms of motivations and willingness to provide/receive care, is crucial to understanding the nature of caregiver and care recipient experiences. A large group of international researchers have co-operated to execute the ENTWINE iCohort-a multinational, transdisciplinary, longitudinal study incorporating intensive methods to examine caregiver experiences in the context of chronic health conditions. The aim of ENTWINE-iCohort is to investigate the broad spectrum of factors, i.e., cultural, personal, geographical, relational, psychological, and economic that may affect motivations, willingness to provide or receive care, among diverse groups of informal caregivers and their care recipients, in different countries that have different care systems. Study questionnaires will be disseminated on-line in nine countries: Germany, Greece, Ireland, Italy, Israel, the Netherlands, Poland, Sweden, and the UK. Cross-sectional and longitudinal multivariate analysis, including intensive longitudinal and dyadic data analysis will be applied to examine the relative contribution of the above factors to caregiver or care recipient wellbeing.