This paper explores the social support networks available to the informal carers of people living with motor neurone disease (MND). An ethnographic case study was undertaken using eco mapping, observation and conversational interviews to collect data from 18 primary carers of people living with MND. Interviews took place in participants' homes in metropolitan, regional and rural locations. Participants discussed the content of their support network and drew lines between individuals to indicate the type and strength of relationship. Changes to the network were depicted on eco maps during subsequent interviews. While health policy-makers assume that healthy social capital exists in Australian communities and that social cohesion will ensure active and available support networks in times of illness or disability, data from this exploratory study indicated that this was not consistently the case. Support networks varied in size and composition; however, age was identified as a discriminator of the availability and consistency of support. People in older age groups identified more diverse but consistent support systems while people in younger age groups reported more fluctuations in the strength of relationships and declines in support as caregiving became more demanding. Individual assessment of support networks at regular intervals in the caregiving trajectory is vital for all carers. However carers in younger age groups may need specific support to manage the psychological crises that occur and more access to paid care. Older carers may need consistent support to handle more of the instrumental aspects of care and assistance to mobilise their support networks. Community workers should be alert to the possible need for crisis intervention when tensions in relationships threaten carers' ability to provide effective care.