This paper analyses data from a 3-year prospective study to understand the factors associated with becoming a caregiver to a person with a chronic illness and examines the dynamics among caregivers over time. A total of 1485 participants were drawn from a study conducted in the slums of Nairobi, Kenya. Two waves of data collected in 2006 for the baseline and a follow-up in 2009 were used. Information on the demographic, self-reported health and socioeconomic characteristics such as education, sources of livelihood and employment status was used. Age was a significant factor in becoming a caregiver, but there were no significant differences by gender or marital status. New caregivers and those with more than one care-giving episode had a higher socioeconomic position than non-caregivers. Caregivers also had poorer health compared with non-caregivers, highlighting the association between being a caregiver and negative health outcomes. Additionally, having cared for someone with a HIV-related illness compared with other chronic conditions increased the likelihood of subsequently caring for another person in need of long-term care. This may be due to the heterosexual mode of HIV transmission in sub-Saharan Africa, hence clustering of infection within family or married couples. This finding draws attention to the need to provide timely interventions to caregivers for people with HIV-related illness who are likely to end up providing care to multiple care recipients. Furthermore, there is a need to enhance the indispensable contribution of informal caregivers through incorporating their role within the continuum of care for effective HIV and AIDS management. Overall, informal caregivers to persons with chronic illnesses perform the tasks of care-giving without any formal support from health or social services. Therefore, it is crucial to initiate policies and programmes to ease the burden of care that is borne by informal caregivers.